GMAT曼哈顿语法总结（自己手打总结）
为了给逻辑和阅读题目留出更多的时间，每道语法题目最好在1分半到1分钟之内完成。需要运用split法进行排除。句首和句尾是split的关键，否则就没必要划线了。
第二章 语法和语义
GMAT句子改错最重要的是语义和语法。语义是句子作者的intended meaning.这种original intended meaning才是句子的真实句义。任何改变句义的选项都是错误的，语义是最最最重要的，通过语法来判断句义是辅助的，所以不能拘泥于语法，而是通过句义来判断作者的原意。所以，可以通过逻辑来找句义，而通过语法来排除那些特别错误的选项。
One of your tasks is to choose the answer choice that transmits the author’s intent as clearly as possible. Don’t alter the author’s intent when you make your choice! (如果句子原文的句义没有错的话，则不能改变句义)
Aggravate aggravating
Known as known to be
Loss of loss in
Mandate have a mandate
Native of native to
Range of ranging
Rate of rates for
Rise raise
Try to do try doing
区别以上词汇的含义区别
句子里任何一个小词的改变，比如虚拟词汇的改变，或者词的位置的改变都会改变句子的含义，所以一定要细细体会这些“小词”的含义。
Will: certain
May: uncertain
Must: absolutely necessary
Should: morally obligated (on the GMAT, should almost always means “morally obligation”, not likelihood)
Would: hypothetical
Pay attention to the original sentence’s helping verbs—and only change them if the original sentence is obviously nonsensical.
句子中任何一个词的位置的变化也会改变句子的含义：
All the children are covered in mud.
The children are all covered in mud.
Only the council votes on Thursdays.
The council votes only on Thursdays.
If a word changes its position in the answer choices, consider whether the change has an impact on the meaning of the sentence. Look out especially for short words that quantify nouns or otherwise restrict meaning
The council granted the right to make legal petitions to city officials.(有歧义，改成：
The council granted CITY OFFICIALS the right to make legal petitions. Or The right to make legal petitions to CITY OFFICIALS was granted by the council.
句子含义一定要合乎逻辑（we must remember that the subject and the verb must make sense together）
句子含义：避免多余（no right answer on the GMAT will contain redundant words）
比较常见的多余的形式是使用同一含义的词，比如：
The value of the stock rose by 10% increase.
应改为：The value of the stock increase by 10%,or the value of the stock rose by 10%.
再如：The three prices sum to a total of $11.56
应改为：The three prices sum to $11.56. Or The three prices total $11.56
表示时间的词汇：要注意一句话中只能出现一次表示同一含义的词，如果还要出现，则必须要有道理才行。(Pure redundancy is always wrong on the GMAT)
Past: previously, formerly, in the past, before now
Present: now, currently, presently, at present
Yearly: annual each year, a year
简洁原则：Concision is preference on SC problems. However, some people are better off never applying it on the GMAT)
自己总结：从逻辑找句义，从语法判断句子是否正确书写，简洁原则是最后关注的），一切都服从句义。
Problem set
1. How matter how much work it may require, getting MBA turns out to
be a wise investment for most people (correct, 但是不太明白那个it代表什么)
2. Even though it requires much work, getting MBA turns out to be a
wise investment for most people(incorrect, 因为它改变了句子的原意)
3. She is the most dedicated gardener on the block, every day watering
the more than 50 plants in her yard.(correct, more than修饰50 plants in her yard)
4. She is the most dedicated gardener on the block, every day watering
more than the 50 plants in her yard.（incorrect, more than 修饰the 50 plants in her yard，隐含的意思是除了给50浇水之外，还给其他东西浇水，改变了句子的含义）
5. Hector remembers San Francisco as it was when he left ten years
ago.(correct,不太明白这句话的含义)
6.Students at Carver High School are encouraged to pursue only those extracurricular activities from which stems success in college applications.(correct,个人认为是倒装，详细见第三章的flip it)
7. Students at Carver High School are encouraged to pursue only those extracurricular activities from which success in college applications stems.(correct, flip it)
第三章 主语和谓语的一致
任何一个句子里，主语和谓语必须在逻辑上和语义上都是make sense的
一、 一个句子中主语和谓语必须都有，否则为fragment:
GMAT错误句子常见方式：
1. drop the verbs: The electron named in 1894.
2. 连词开头且没有主句：because the dog was never mine
二、 主语和谓语必须合理make sense
The development of a hydrogen car based on expected performance parameters will be able to travel hundreds of miles without refueling.(incorrect)
Once developed, a hydrogen car based on expected performance parameters will be able to travel hundreds of miles without refueling.(correct)
三、 主语和谓语必须在数量上一致
GMAT often tries to confuse you before you make the subject-verb match.
如何找句子中的主语呢：
1. eliminate the middlemen, and skip the warmup
GMAT hides the subject in a few ways: the most common way by far is to insert words between the subject and the verb:
介词短语：(Near Galway), the houses (on the road to Spiddle) are gorgeous.
从句：（like prepositions phrases, many subordinate clauses modify other parts of the sentence, acting as big adj or big adv. Some subordinate clauses even act as big nouns）
(When the auditors left), the executive (who had been interviewed) was glad.
其他修饰语：例如现在分词，过去分词等修饰语，往往利用逗号可以很好的找到修饰语。
(Limping,) the horse (once considered one of the favorites) was taken away.
2.利用结构来判断主语
A noun in a prepositional phrase can not be the subject of the sentence.(后文有例外)
In the waning days of the emperor’s life, the conquest (of new lands on the borders of the empire) was considered vital.
The tidal forces (to which an object falling into a black hole is subjected) are sufficient to tear the object apart.
3. And vs. Additive phrases
只有AND改变主语的复数形式，其他表示“和”的词语都只是修饰，可以省略看待。
Additive phrases: along with, in addition to…, as well as …, accompanied by …, together with…, including …
Only the word and can change a singular subject into a plural one. Singular subjects followed by additive phrases remain singular subjects.
Example: Joe, as well as his friends, is going to the beach.
Mathematics, in addition to history and sciences, is a required subject.
表示“学科、疾病、一些活动（如杂技）”等词都是单数形式。
Rules:
（1）Or, either…or, neither …nor: 就近原则
Neither the coach nor the players are going to the beach.
Neither the players nor the coach is going to the beach.
（2）Either, neither…:总是单数
（3）集合名词：总是单数：
Agency, army, audience, class, committee, crowd, orchestra, team, baggage, citrus, equipment, fleet, fruit, furniture…
（例外：如果句义强调集合名词中的个体，则使用复数，但是本考试中，结合名词一般是单数的含义）
The crowd in the stands is cheering loudly as the home team takes the field.
Our Army of a hundred thousand soldiers is attacking the enemy.
（4）不定代词：总是单数
Anyone, anybody, anything, no one, nobody, nothing, each, every, someone, somebody, something, everyone, everybody, everything, whatever, whoever, either, neither(单独使用)
例外：some of , any of , none of, all of, more of, most of…
谓语动词视后面的名词而定。（sanam of…的主语是后面的名词）
Some of the money was stolen from my wallet
Some of the documents were stolen from the bank
Any of these women is a suitable candidate for marriage to my son.
Not one of my friends is here this weekend.
(5)each, every: 总是单数
Every dog has paws.
Every dog and cat has paws.
Each of these shirts is pretty.
注意：They each are great tennis players. Each是插入语，可以省略。
(6) 数量词和短语
The number of … is (单数，主语是the number)
A number of…are(复数， 主语是复数)
表述数量的词，如： half, majority, minority, plurality谓语动词的形式看其前面的名词是复数还是单数。 （原则同sanam+of短语）
Half of the pie is blueberry, and half of the slices are already gone.
The majority of the students in this class are hard workers.
In the Senate, the majority has coalesced into a unified voting block.
（7）主语从句和短语：谓语动词总是单数
Having good friends is a wonderful thing.
Whatever they want to do is fine with me.
3. flip it 倒装句的谓语动词总是看其真正的主语，跟主语的数的形式一致
Near those buildings sits a Lonely house, inhabited by squatters.
There are a young man and an older women at the bus stop.
Pong is a classic game from which have descended many current computer pastimes.
Problems set
Computer games designed to involve many players at once have proliferated; such games were first developed before the widespread availability of high-speed internet connection. (correct, 主语和谓语逻辑合理)
第四章 平行结构
Gmat中考得最多的知识点就是平行结构
一、 平行结构的指示词
最主要的平行指示词是and, but, or,然而不要拘泥于这样的结构，any construction that expresses two or three things in the same way requires parallelism.
二、 哪些东西可以平行呢？
名词、形容词、动词、不定式、分词、介词短语、从句
The division was opening offices, hiring staff, and investing in equipment.
The railroad can either lose more money or solves its problems.
They wanted to increase awareness, spark interest, and motivate purchases.
I want to retire to a place where I can relax and where I pay low taxes.
There are many people who speak English but whose parents do not.
Ralph likes both those who are popular and those who are not.
三、 and 的用法
在所列事务中最后一个前面必须加AND， 如果是2个从句，则两句话中间可以在AND前加逗号，也可以不加。If you join 2 clauses with and, you can put an optional comma before the and.（如果句子很长，且独立，则需要加逗号）
I really like candy apples, and I eat them often.
She argues that the agency acts with reckless abandon and with disregard for human life and property, and that it should therefore be shut down.
四、 其他类型的平行结构指示词
五、 表明的平行结构与真实的平行结构
虽然在表面上看是从平行结构的指示词中看出是平行结构，但是实际上，是从句子的句义中看出是不是平行结构的，也就是说虽然句子有平行结构的指示词，但实际上也许不是平行结构，所以一定要从句义着手判断。
Sal applied himself in his new job, arriving early every day, skipping lunch regularly, and leaving late every night.
本句的平行结构指示词是and, 平行的部分是分词skipping, leaving，这两个现代分词作applied的补充。
Sal applied himself in his new job, arrived early every day, skipped lunch regularly and left late every night. 这是错误的句子，因为它把skip, arrive当作和applied 同等的词，其实并不是这样，他们是补充，所以必须要用现在分词。
六、 注意系動詞
Linking verb也是平行结构的指示词
系动词平行的部分在含义上，在逻辑上都必须合理
The nomination of this politician represents a step forward in urban-rural relations in this country.
Note that the verb to be does not have to be part of a linking verb phrase. The verb to be also forms the progressive tenses and the passive voice. Do not look for parallelism in these uses of be.
Problem set
1. The students did poorly on the test more because they had not studied than because the material was difficult.
2. The experiences we have in childhood influenced our behavior in adulthood.
3. Although we were sitting in the bleachers, the baseball game was as exciting to us as to the people sitting behind home plate.
4. Voters want to elect a president who genuinely cares about health care, the environment, the travails of ordinary men and women, and who has the experience, wisdom, and strength of character required for the job.
5. The consultant is looking for a café that has comfortable chairs and that provides free internet access.
第五章 代词
GMAT中经常考代词，代词和先行词必须都有，在数量上和逻辑上都必须合理。
The rangers discussed measures to prevent severe wildfires, which would be devastating to the park.
注意在名词所有格的名词不能作为代词的先行词。（非常重要）
Watch out for nouns used as adj, they cannot be antecedents of pronouns.
The antecedent to which you want to refer must actually exist in the sentence as a noun.
一、 先行词和代词必须合理
逻辑上合理：Although the term “supercomputer” may sound fanciful or exaggerated, it simply refers to an extremely fast mainframe that can execute trillions of calculations every second.
代词与其先行词必须检查是否合理。
二、 先行词与代词必须在数量上合理
Confronted by radical changes in production and distribution, the modern Hollywood studio is attempting various experiments in an effort to retain its status as the primary arbiter of movie consumption.
三、 五个比较容易错误的代词：it, its, they, them, their
凡看到句子中的上述五个单词，则必须找到其先行词，看其合理性。
Whenever a student calls, take down his or her information
Whenever students call, take down their information.
四、 指示代词this, that, these, those
这些都是形容词，放在名词前面
New nano-papers incorporate fibers that give these materials strength.
That,those 可以代表new copy
The money spent by her parents is less than that spent by her children.
从中可以看出，两个MONEY是不同的，不是同一个MONEY
与此相比，如果用it, they或其他个人代词，则指的是同一个事情：
The money spent by her parents is more than it was expected to be.
That or those indicating a new copy or copies must be modified.
Her company is outperforming that of her competitor.
Gmat认为that,those 与之前的先行词在数量上一致。
Her company is outperforming the companies of her competitors.
不能用this, these来代替名词
Her products are unusual; many consider them unique.
五、 如果代词出现混乱、歧义怎么办？
理论上讲：任何句子中的代词都应该指代同一个名词，否则就会出现歧义和混乱。
e.g. Researchers claim to have developed new “nano-papers” incorporating tiny cellulous fibers, which THEY allege give THEM the strength of cast iron. (wrong)
Researchers claim to have developed new “nano-papers” incorporating tiny cellulous fibers, which give these materials the strength of cast iron, according to the researchers.
如果出现一种情况，即：一个句子中出现only one pronoun but more than one possible antecedent?
Gmat有时会容许有“代词的歧义”现象出现。因为英语语法是容许的。
If the intended antecedent of a single pronoun is clear, and if there is no other reasonable antecedent, then don’t worry if there is an unreasonable antecedent somewhere else in the sentence.
E.g. Supernovas destroy their immediate environments in vast explosions, but by synthesizing heavy chemical elements, they provide the universe with the possibility of biochemistry-based life as we know it.
上面的句子中，THEY指的是supernovas，因为在but引导的并列的两个句子里，主语都是一致的，所以尽管句子中也出现了其他复数名词，比如elements和environments，但是由于并列句子的关系，第二个句子的主语就是第一个句子的主语。所以：the subject is the most important noun in the sentence; thus, it makes the best antecedent.
所有格形式在句子中通常都是不太好的先行词。
The board is investigating several executives’ compensation packages in order to determine how much may have been improperly awarded to them.
这里的them指的是packages, 但实际上应该指executives.
The board is investigating the compensation packages of several executives in order to determine how much THESE EXECUTIVES (they) may have been improperly awarded.
原则：在一个句子中，每个it, its 一定是指代同一个单数先行词，每个they, them, their 一定指代同一个复数先行词。
Don’t apply pronoun ambiguity unless you are backed into a corner.
上述的句子中选择these executives会更为安全。
第六章 修饰词
修饰词的分类:
Noun modifiers:修饰名词的词叫做Noun modifiers
包括：形容词、介词、过去分词、现在分词、从句和名词
Verb modifiers:修饰动词的词叫做Verb modifiers
包括：副词、介词、从句
个人思考：
修饰词是GMAT最喜欢考的考点，因为它通常会出错：
原则一：修饰词必须有可修饰的词，也就是说如果发现一句话中修饰词找不到可修饰的东西，则该句错误。换句话说就是修饰词和被修饰的东西必须合理，有逻辑。（dangling modifier）
在看到一句话之后找到修饰词和它所修饰的东西，看是否合理，是否MAKE SENSE,如果不合理，则该句有问题。(换句话说看修饰语与被修饰语是不是作者的原意)
原则二：TOUCH原则 a noun and its modifier should touch each other
Misplaced modifier(此原则只适用于noun modifier)
形容词：只修饰名词/代词
副词：可修饰除名词/代词之外的其他词，包括动词、形容词、介词、从句等
形容词和副词到底用哪个需依据句子的原意和作者的写作意图来定，不能颠倒。
举例：James Joyce is Max’s supposedly Irish ancestor.(wrong)
James Joyce is Max’s supposed Irish ancestor.(correct)
本句的重点是ancestor，而非Irish，所以应该用supposed来修饰ancestor，而不是用supposedly来修饰Irish。为什么？因为James Joyce may or may not be Max’s ancestor, but James Joyce was certainly Irish.
举例：Max’s grandmother is his supposed Irish ancestor.
Max’s grandmother is his supposedly Irish ancestor.
本句的重点是whether Max’s grandmother was Irish, not whether she is Max’s ancestor. 因此，我们需要用supposedly 来修饰Irish.
类似的形容词和副词互换有：
Corresponding, frequent, independent, rare, recent, seeming, separate, significant, supposed, usual.
形容词+形容词+名词。。。。。。。。。。。。副词+形容词+名词 （具体哪个看作者的意图）
系动词之后必须跟形容词，不能跟副词。
Amy is a good person(good 形容词修饰amy)
Amy is feeling good.(good 形容词修饰Amy)
Amy is feeling well.(well形容词修饰amy)
Amy writes well.(well副词修饰writes)
Noun modifiers情况下，很多情况下，句子用逗号将noun modifier与主句隔开，所以，需要格外注意opening modifier,经常出现在句子之首。需要注意是不是合理。（有没有被修饰词以及是否搭配合理）
e.g. Tired from chasing mice, the cat took a nap.
GMAT loves to play tricks with these kinds of modifiers.
Appositive同位语：A lover of mice, my cat hunts night and day.
When you see a noun modifier, ask yourself what noun should be modified. Then check to make sure that the modifier is next to that noun.
e.g. To get to his house, Jim biked along an old dirt road, which cut through the woods. (correct)
Jim biked along an old dirt road to get to his house, which cut through the woods.(wrong)
If the noun we want to modify is not even in the sentence, we have a dangling modifier
e.g. There was no commotion in the office, resigned to the bad news.(wrong)
Resigned to the bad news, the office workers made no commotion.(correct)
名词修饰语的位置
一个名词与其修饰语必须TOUCH each other.
两种错误的名词修饰语:
(1) misplaced modifier
Jim biked along on old dirt road to get to his house, which cut through the woods.
which cut through the woods.错误的修饰了his house.
To get to his house, Jim biked along an old dirt road, which cut through the woods. (correct)
(2)dangling modifier
Resigned to the bad news, there was no commotion in the office.(wrong)
There was no commotion in the office, resigned to the bad news. (wrong)
Resigned to the bad news, the office workers made no commotion.(right)
注意当a present participle(-ing form)出现在句首的时候，通常情况下会是无修饰词。
e.g. Using the latest technology, the problem was identified.(wrong)
Using the latest technology, the engineers identified the problems.(correct)
Unlike a noun modifier, a verb modifier does not have to touch the subjects.
Both shocking and entertaining audience across the nation, George Carlin influenced and inspired a generation of comedians, even as the struggled publicly with drug abuse.
Both shocking and entertaining audience across the nation,与他所修饰的G. C. 联合在一起，解释g.c.如何influence and inspired.
注意所有格形式
Misplaced modifiers sometimes appear in sentence that have possessive nouns (nouns that end in ‘s or s’)
E.g. Unskilled in complex math, Bill’s score on the exam was poor. (wrong)
Unskilled in complex math, Bill did not score well on the exam. (correct)
要格外注意一些抽象名词，例如development，modifier that touch them should be intended to modify them.
e.g. Only in the past century was origami’s development, a ceremonial activity invented millennia ago, into a true art form taken place. (wrong)
Origami—a ceremonial activity invented millennia ago—has developed into a true art form only in the past century. (correct)
名词性修饰语与关系代词
关系代词：which, that, who, whose, whom, where, when,
需遵守的规则：
1. who and whom must modify people
2. which must modify things.
3. That 不能modify people
4. Whose can modify either people or things: the town whose water supply was contaminated.
5. Which 和whom有时跟着介词，the canal through which water flows. The senator for whom we worked.
6. Who作为定语从句的主语，whom作为宾语
The security whom we met was nice.
7. That and whom当引导宾语时可省略：the movie that we watched last Friday was scary. The movie we watched last Friday was scary.
8. Where 可以修饰一个地点名词，比如：area, site, country, where 不能做“比喻”的含义，如果要修饰condition, situation, case, circumstances, arrangement 要用in which 而不是where.
We had an arrangement in which he cooked and I cleaned.
9. When 可以修饰a noun event or time, such as period, age, 1987, or decade, 在这种情况下也可以用in which来代替。
Essential vs. non-essential noun modifiers
Noun modifiers are either essential or non-essential
Essential modifiers
提供的necessary information to identify the noun or to attach the modifier to the noun from that point onward.
e.g. The mansion painted red is owned by the Lees.
这里必须用essential modifier，因为如果不用的话，则不知道说的到底是哪个mansion.(这也是essential modifier使用上的重点和难点，需要identify noun的时候就需要用essential modifier)
Non-essential modifiers
提供多余的信息，you do not need this information to identify the noun, since it is already identified in some other way.
e.g. This mansion, recently painted red, is owned by the Lees.
“this”已经指出了到底是哪个mansion, 所以后面的recently painted 是non-essential modifiers.
Put commas between non-essential and their nouns;
Put no commas between essential modifiers and their nouns.
E.g. This mansion, which has been recently painted red, is owned by the Lees.
The mansion that has been recently painted red is owned by the Lees.
Gmat不会把which和that当作是选择的唯一点，因为他们的使用 有分歧。
“who” can be used in essential or in non-essential modifiers.
Verb modifiers
动词修饰语修饰的动词，these modifiers answer questions about the verb, such as “how, when, where, why” etc. The most basic verb modifier is an adverb. Other verb modifiers act in much the same way as adverbs.
从属连词包括because, although, if, unless, while, so that, while, and so on.这些从属联系必须和主句attach在一起。
有一些动词修饰语可以和动词以及动词的主语连在一起，这时一定 要注意make sure that the subject makes sense with the modifier.
e.g.
现在分词： Whistling beat it, I lifted the weight.
介词+简单动名词：By concentrating, I lifted the weight.
不定式：To free my leg, I lifted the weight.
I lifted the weight to free my leg.
Make sure that these modifiers have a sensible subject in the sentence.
Wrong： The weight was lifted by concentrating.
注意不定式的用法和含义：
Infinitives of purpose can be used with unnamed agents in passive-voice sentence: the weight was lifted to free my leg. Just make sure that whoever does the lifting intends to free my leg.
An infinitive of purpose needs to indicate the purpose of someone.(不定式的主语需要指出到底谁是“目的”的主语)The boulder rolled to free my leg implies nonsensically that the boulder wanted to free my leg. (the boulder是to free my leg的主语，所以是不合乎逻辑的)
虽然动词修饰语不像名词修饰语那样必须遵守touch rule,但是其实它也必须跟所修饰的动词放在合理的位置，否则就会产生歧义：
The nameless symphony was at last performed, decades after it was composed, yesterday. (错误的将yesterday放在最后，没有合理的修饰performed)
The nameless symphony was at last performed yesterday, decades after it was composed. (yesterday修饰的是was performed，合理的位置不会引起歧义)
（引申：真题中很多情况下出现类似的错误，副词或介词短语是如何才能更好的修饰动词是个重点，很多时候是语感的问题）
Which vs 现在分词-ing形式
Which一定是修饰which之前的名词的，use which only to refer to the noun immediately preceding it---never to refer to an entire clause.
e.g. The recent decrease in crime in our neighborhood has led to a rise in property values. (correct )
Crime has recently decreased in our neighborhood, leading to a rise in property values. (correct )
--ing的用法：
现在分词的使用非常灵活：
可以修饰名词：the changing seasons
可以修饰动词或他们的主语： I lifted the weight, whistling
可以修饰整个句子：Crime has recently decreased in our neighborhood, leading to a rise in property values.（表达前面一个句子的结果）
经常犯的错误是用which来代替前面一个句子，而不是名词。
Always test which clauses to make sure that the “which” refers to the noun immediately preceding the “which.”
第七章 时态、语气和语态
时态：
一般时态：
一般现在时：to express the eternal states or frequent events, general rule.Gmat比较偏爱一般时态，除非句子很明显的要求一个或更多复杂的时态
一般过去时：
一般将来时：
进行时态:to emphasize the ongoing nature of an action
E.g.Sandy is playing soccer.
Sandy was playing soccer yesterday.
Sandy will be playing soccer tomorrow.
现在进行时表示正在进行的动作。
一般时态表示经常做的动作，或者某人知道如何做什么
Sandy plays soccer:
She frequently plays, or that she knows how to play.
表达GENEARL RULE（definition）的时候用一般时态，不能用进行时态
Cherenkov radiation is light that particles emit when they travel faster than the effective speed of light in any medium.(用一般现在时，不能现在进行时)
表达将来发生的动作时应该用一般将来时，不能用现在进行时
Quentin will meet Harvey for lunch tomorrow.
一些表达general state 的单词没有进行时态，要用一般时态
这些词包括：know, signify
e.g. This inscription signifies the emperor’s birth.(is signifying是错误的)
时态应反映句子含义
Sometime, all the tenses in a sentence are the same, because all the actions take place in the same timeframe. However, in some sentences the author clearly wants to talk about different periods of time. The tense should change to reflect that intention.
e.g. He is thinner now because he went on a strict diet six months ago.
Sometimes, you can use the past progressive to describe a background event, while you use simple past to describe a more important event in the foreground.
e.g. She was playing with her friends when the babysitter arrived.
上面的句子中，playing with her friends是babysitter arrived的背景。当她与她的朋友们玩的时候保姆来的。
e.g. She played with her friends when the babysitter arrived.
Played with her friends发生在babysitter arrived的之后，所有两个动作都是一般过去时，表达的动作重要性一致。
选择动词的时态作为句子选项的时候必须要牢记一点：every verb’s tense clearly represents the author’s intention.(作者想表达什么样的意思才是选择哪种时态的选择标准)
完成时态：
有时一些句子里需要混用不同时态来表达不同时点的含义，这时需用完成时态。
(1) 现在完成时：still in effect…
We use the present perfect tense for actions that started in the past but continue into the present, or remain true in the present. The Present perfect tense has one foot in the past and one foot in the present.
e.g. We have lived in a hut for three days.
含义是：我们三天前就开始住在小屋里，直到现在。
e.g. We lived in a hut for three days.
含义是：我们三天前就开始住在小屋里，现在不住了。
注意过去分词的拼写。
e.g. This country has enforced strict immigration laws for 30 years.
Enforced的动作发生在30年前，并且一直持续到现在。
They have known each other since 1987.
他们自从1987年就认识，并且持续到现在。
有时候，现在完成时意味着某动作已经结束，但是它的影响还存在着。
e.g.The child has drawn a square in the sand.
上面句子中，儿童画画的动作draw已经结束了，但是这个画的影响还存在着，也许他画的正方形还存在着。
如果他画的那个正方形已经消失，则应使用一般过去时：
The child drew a square in the sand, but the ocean erased it.
正方形的现状不知道，一般过去时。
The child drew a square in the sand, but the ocean has erased it.
正方形不再存在，因为has erased表示这个erased 的影响还在存在。
The child has drawn a square in the sand, but the ocean has erased it.
(wrong)因为时态含义前后矛盾。
小结：The Present Perfect indicates either continued action or continued effect of a complete action up to the present.
几个比较常见的表示现在完成时的关键词：
Since, within the past..., in the last…同时，a time phrase that does not include the present (last month, in 2007, etc…) prevents the use of the Present Perfect. Use the simple past instead.
e.g. Since 1986 no one has broken that world record.
Veronica travelled all over the world in 2007.
The present perfect can be used in –ing forms, infinitives or subordinate clauses to clarify an ambiguous sequence in time.
When can mean either “at the same time” or “after”.
仔细体会:
She will pay you when you ask her.
=she will pay you at the same time as you ask her, or maybe just after.
She will pay you when you have taken out the garbage.
=she will pay you clearly after you take out the garbage and have proven it.
现在完成时有种动作完成的概念。
（2）过去完成时
如果在一句话中出现2个不同时间点的动作，我们经常使用过去完成时来表达较早之前的动作，用一般过去时表达稍微之后发生的动作。过去完成时是过去的过去。
The film had started by the time we arrived at the theater.
Arrived 发生在电影开始之前，而电影开始也已经是发生过的事情了。
The teacher thought that Jimmy had cheated on the exam.
Jimmy作弊发生在老师thought之前，老师thought已经是发生的事情了。
过去完成时用于很久之前的事情，但是必须有个时间点参照，即使是很久之前的事情，如果没有后来的时间点参照也是不能用过去完成时的。
e.g. An asteroid STRUCK the earth millions of years ago.
什么情况下使用过去完成时：
In general, you should use Past Perfect only to clarify or emphasize a sequence of past events. The earlier event should somehow have a bearing on the context of the later event. If the sequence is already obvious, we often do not need past perfect.
Antonio DROVE to the store and Cristina BOUGHT some ice cream.
Antonio drove to the store and bought some ice cream.
我们不需要用过去完成时，因为没有想强调这两个动作的顺序的意图。
一般来讲，用and or but来连接的句子不需要使用过去完成时。
Laura locked the deadbolt before she left for work.
这里无需使用过去完成时，因为before, after这样的词语已经把动作的时间顺序表达清楚了，所以没有必要利用过去完成时来表达这一顺序。
E.g. By 1945, the United States HAD BEEN at war for several years.
用by 1945来表达时间点，并且表达continued effect.
完成时态：只在必要的时候使用
只要一般时态可以说清楚就不用完成时态。GMAT偏爱简单。
Joe learned about an epoch in which dinosaurs had walked the earth.
这里使用过去完成时是没有必要的，因为the earlier action does not have a direct bearing on the context of the later action. The sequence of time does not need to be clarified or emphasized. Thus, 过去完成时在这句话中是错误的。
使用完成时的原则：you should use the perfect tenses only when you can justify them with the rules:
当一个动作发生在过去，且一直持续到现在，或其影响一直持续到现在，使用现在完成时，
当一个动作发生在另外一个已经发生的动作之前，且需要强调这两个动作的先后顺序时使用过去完成时。其他情况下只用简单的时态。
e.g. The scientists announced that the supercollider was ready, that it had not cost too much, and that it would provide new insights into the workings of the universe.
小结： conditional tense: would + verb
过去时+conditional tense
The scientists believed that the machine would be wonderful.
现在时+will
The scientist believes that the machines will be wonderful.
注意不要mix them
虚拟语气
Indicative mood：陈述语气
Imperative mood:祈使句、命令句
虚拟语气（subjunctive mood）的两种使用：
(1) unlikely or unreal condition(if, as if , or as though或类似的句子之后)
(2) proposals, desires, and requests formed with certain verbs and the word that.
The Hypothetical subjunctive假设虚拟
表达unlikely or unreal condition(if, as if , or as though或类似的句子之后)
To overcome my fear of germs, I will think about disease as though it were harmless.
说话人并不相信疾病实际上是无害的，他只是虚拟假设认为疾病无害。
Were的使用： If I were a rich man, ……
If…then…结构：记住如下的结构:
(1) general rule with uncertainty
If Sophie eats pizza, then she becomes ill.
if现在时，then现在时
Whenever S eats pizza, she becomes ill.
(2) general rule with some uncertainty
If S eats pizza, then she may become ill.
If现在时，then can or may
Uncertain outcome
(3) particular case with no uncertainty
If S eats pizza tomorrow, then she will become ill.
If 现在时，then 将来时
另外一种可能性：If S has eaten pizza, then she will become ill.
(4) Unlikely case(in the future)
If S ate pizza tomorrow, then she would become ill.
含义是：作者认为S不太可能明天吃披萨，the conditional tense(would)shows the hypothetical result of an unlikely or untrue condition. Would可以用could 代替。
(5) Case that never happened(in the past)
if past perfect, then conditional perfect.
上述5中if…then…表达方式可以涵盖gmat中出现的结构。
命令式虚拟语气
Bossy verbs+that+subject+command subjective
We propose that the school board disband.
注意不是每个bossy verb都用虚拟语气，一些BOSSY VERB不用虚拟语气，比如want等，具体哪些是习惯。
Command verbs that take only the command subjunctive when indicating desire:
Demand, dictate, insist, mandate, propose, recommend, request, stipulate, suggest
e.g. we demand that he be here.
Propose可以使用不定式结构，在没有第二个主语的情况下。
The attorneys proposed to meet the following day.
Verbs that take only the infitives:
Advise, allow, forbid, persuade, want
e.g. we allow him to be here.
Verbs that take either the command subjective or the infinitive.
Ask, beg, intend, order, prefer, urge, require.
Prohibit from doing sth.
Bossy verbs 的变形也用虚拟语气，比如demand, request.
His demand that he be paid full severance was not met.
一些形容词也用于虚拟语气：advisable, crucial, desirable, fitting, imperative, important, mandatory, necessary, preferable, urgent, vital同样，这些词后也可以跟不定式。
It is essential for Gary to be ready before noon.
Whether之后不用虚拟语气
I like ice cream, whether it is chocolate, vanilla, or any other flavor.
一些BOSSY VERBS可以用于NON-BOSSY WAYS:
比如suggest，并不是一看到suggest就一定要用虚拟语气，要看具体含义：
Her presence suggests that she is happy.这里suggests是means的含义。
主动语态与被动语态
Whoever actually performed the action in the sentence may follow the verb in a phrase headed by the preposition by (by the hungry students). Use by only for the actual doers of the action. Use through or because of when you want to describe any instrument or means, which might be an awkward or nonsensical subject in active voice.
e.g. The pizza was accidentally eaten by a quirk of fate.(wrong)
A quirk of fate accidentally ate the pizza.(wrong)
Through a quirk of fate, the pizza was accidentally eaten.
如果BY这个词在文中非划线部分出现，则可以考虑使用被动语态。
News of the moon landing was repeated around the world by people of all ages, all races, and all religions.
注意：只有及物动词才能有被动语态的形式。不及物动词没有被动语态。
The aliens were arrived on Neptune in the 20th century.（wrong）
The aliens arrived on Neptune in the 20th century. (correct, arrive是不及物动词)
被动语态永远是正确的吗？
The answer is YES, quite often, voice is a matter of choice.
It has been decided by Jason that he will not attend college.
Jason has decided not to attend college.
上述两个句子都是正确的，但是主动语态的句子更加正确一些。人们通常认为被动语态往往是错误的，但是GMAT正是利用了这一点把被动语态的句子弄得看起来比较奇怪，但是实际上是正确的。
It has been decided by Jason that he will not attend college next fall.
Jason has decided next fall not to attend college.
上面两个句子第一个是正确的，因为第二个句子中的next fall和动词has decided连在一起，让人误以为是“明年秋天决定。。。。”错误的更改了作者的含义。
所以，不能对被动语态有偏见，不要利用语态来区别不同的答案。
如果在两个语态中选择的话，没有其他好选的情况下，就选择被动语态，你可能在主动语态中错过了错误的地方。
被动语态的句子并不是很“难看”，有时它是好的句子：
During the operation, new blood vessels are inserted around blockages.
As a final note, you do not have to make active or passive voice parallel throughout a sentence:
The shuttle launch took place flawless and was seen on television.
第八章 对比
Once you find a comparison, identify the two parts of the sentence that are being compared to each other.找到对比的两个部分。这句话特别重要，也就是说正确的对比的句子都是有两个或多个部分的对比的。必须要找出哪个和哪个对比。这些对比的句子都是在结构和逻辑上平行的。
主要对比的标志词包括：like, unlike, as, than
Like vs.As
(1)Like是非常重要的对比的标志词，它是一个介词，所以，它之后必须跟名词、代词和名词短语，不要跟从句或介词短语，like不能对比两个名词。
Like her brother, Ava aced the test.(correct)
Like之后可以跟动名词：
Like swimming, skiing is great exercise.
(2)as是既可当介词（后跟名词）又可当连词（后跟从句），as可以用来比较2个句子
As her brother did, Ava aced the test.
在含义上，like her brother, Ava aced the test.和As her brother did, Ava aced the test.没有区别。
保持对比部分的平行
原则1、对比部分必须在逻辑上平行，就是说对比部分必须是similar things
Frank’s build, like his brother, is broad and muscular.
比较的内容不同，Frank’s build 与her brother不能比较。
Frank’s build, like his brother’s, is broad and muscular.
对比的内容一致。
That和those 代表build. That代表单数，those代表复数。
Frank’s build, like that of his brother, is broad and muscular.
Frank’s toes, like those of his brother, are short and hairy.
Frank, like his brother, has a broad and muscular build.
Beethoven’s music, which broke a number of established rules with its structure and melodic form, is considered more revolutionary than Bach’s.
对比必须是在结构上平行，也就是说他们必须有相似的语法的结构
I like running through forests more than walking through crowds.(correct)
省略：
对比的句子第二部分往往会出现省略。通常用所有格形式来代表。
My car is bigger than Brian’s(car).
My car is bigger than the Smiths’(car).
所有格Brian’s或是Smiths’是单数还是复数都可以，根据实际情况，但是必须要保证对比的内容要在逻辑上和形式上一致。
同样也可以省略单位units,动词verbs,甚至整个句子whole clause（在对比的第二阶段），只要不产生歧义。
e.g. Whereas I drink 2 quarts of mile a day, my friend drinks 3(quarts).
I walked faster than Brian(walks).
I walk as fast now as I (walked)when I was younger.
In general, you should put in the omitted words or appropriate Helping Verbs (such as be, do, and have)only if you need to remove ambiguity.
Vishal eats more carrots than donuts.(省略he does，因为donuts很显然是宾语，不会出现歧义)
Vishal eats more carrots than HE DOES donuts.(wordy)
e.g
I like cheese more than Yvette.(Yvette可以是主语也可以是宾语，所以必须修改以消除歧义)
I like cheese more than Yvette Does.(than Yvette likes cheese)
I like cheese more than I do Yvette.(than I like Yvette)
GMAT有时许可unnecessary helping verb in the second term of a comparison.
比较级和最高级形式的对比：
当比较2个事务时用比较级，当比较3个或以上事物时用最高级。
She is shorter than her sister.
She is the shortest of her five siblings.
You are more interesting than he.
You are the most interesting person here.
注意形容词或副词比较级和最高级的特殊形式。
副词以ly结尾的，比较级用MORE
Adrian runs quickly. He runs more quickly than Jacob.
有些副词没有以LY结尾的，换成比较级时结尾加er
Adrian runs fast. He runs faster than Jacob.
用比较级时句子中一定必须有than
I will have HIGHER bills over last year.(错误)
I will have higher bills than last year.（正确）
Always use than with a comparative form.
第十章 标点符号
一、 连词
一个正确的句子必须包含至少一个主句，该主句必须有主语和谓语。也就是说如果一个句子没有主语或谓语，该句子就是一个错误的句子。一个缺少主句的句子叫做fragment.
有时一个正确的句子包含2个或以上主句。这样的句子之间用连词或标点符号链接。链接错误的句子叫做run-on sentence.
e.g. I need to relax, I have so many things to do.
这个句子就是一个run-on sentence. 因为逗号并不能链接两个句子。
e.g.I need to relax, but I have so many things to do.
这个句子就是正确的句子，因为它有正确的连词but连接。
Coordinating conjunctions:
And, but, or, for, nor, yet, so，这些连词加上逗号，可以合理的连接两个主句。
切忌：单独一个逗号不加其他连词是不能连接两个主句的。
e.g. new data from ….indicate that producer prices rose rapidly last month, some analysts contend that ….
这个句子是错误的，因为它只用了一个逗号链接两个主句。
正确的句子：New data from…indicate that….but some analysts contend that….
And是个非常重要的连词，当看到and时应该想到两点：
第一、 罗列清单：apples, grapes, and pears
第二、 两个主句的链接：I like apples, and she likes grapes.
（注意and及前面的逗号的位置,and连接的是两个主句，所以必须有主语和谓语）
Subordinators :是另外一种连词，包括：because, although, 从属连词链接的是一个从句，有从句必有主句。
e.g. I need to relax, because I have so many things to do.
使用连词的原则：
第一、 一次只是用一个连词：
Although I need to relax, yet I have so many things to do.(wrong)
Although I need to relax, I have so many things to do.(correct)
I need to relax, yet I have so many things to do.(correct)
原则二、连词的使用要合理，合乎逻辑：
She is not interested in sports, and she likes watching them on TV.(wrong)
Although she is not interested in sports, she likes watching them on TV.
（correct）
原则三、一定要确保句子中的各个成分的一致性和合理性。
二、 标点符号
包括：逗号，分号，冒号，破折号
逗号：最最要的标点符号之一
逗号的作用：separators of modifiers, items in a list, and other sentence elements.
e.g. non-essential modifiers should be separated by comma.
“this car, purchased last year, is a Buick.”
值得注意的是：同一个主语的两个动词之间不能用逗号
She walked to school, and later ate her lunch.(wrong)
She walked to school, and she later ate her lunch.(wrong)
She walked to school and later ate her lunch.(correct)
另外，之前强调过单用逗号不能连接两个主句
She walked to school,she later ate her lunch.(wrong)
特例句子：the bigger they are, the harder they fall.
分号：分号链接的是两个相互联系的句子，每个句子必须独立句子
She walked to school; he later ate his lunch.（正确）
Lisa and Alice are inseparable; doing everything together.
后半句话不是独立的，所以上述句子错误
Lisa and Alice are inseparable; they do everything together.
上述句子是正确的，应为两个句子都是独立存在的，可用分号隔开。
值得注意的是：使用分号必须是两个句子是相互有关系的，且是独立和平衡的关系。（two sentence parts are related in an independent, balanced way）如果作者的初衷是一个句子是另外一个句子的从属，那么就不能用分号，必须用从句（从这个角度上讲，句子的含义是一个句子使用什么标点的出发点）
e.g. the dam has created dead zones, where fish have disappeared.(correct)
the dam has created dead zones; fish have disappeared(wrong)
分号的使用往往跟一个连词副词或其他过度词（如：however, therefore, in addition）这些过度词并不是真正的连词（AND）,因此，必须使用分号，而不是逗号来链接两个句子。
正确的句子：
Andrew and Lisa are inseparable; therefore, we never see them apart.
分号另外的作用是区分本来已经包含逗号的词：
I listen to Earth, Wind and Fire; Wow, Owls; and Blood, Sweat and Tears.
冒号：作用是对于之前的东西给予解释。
比如可以使用冒号来罗列清单及其组成部分，可以使用namely or that is after the colon.
冒号之前的句子必须是一个完整的句子，冒号之后的句子可不是完整的句子。
I love listening to: classical, rock, rap, and pop music. (wrong)
I love listening to many kinds of music: classical, rock, rap, and pop.(correct)
I love listening to many kinds of music: namely, classical, rock, rap, and pop.(correct)
需要解释的内容需与冒号尽可能靠近
The rate of a reaction is affected by three factors: concentration, surface area, and temperature. (correct)
此外，在冒号之后可以有一个主句，主句是解释冒号之前的句子的—也许是之前一个整个从句。
On Jan, 1, 2000, the national mood was completely different from what it would become just a few years later: at the turn of the century, given a seemingly unstoppable stock market and a seemingly peaceful world, the country was content.(correct)
分号：连接两个相关的句子，后句不见得解释前一句
冒号：链接两个句子，后一句是解释前一句的。
破折号：
作用1、使用较灵活，可以作为强调作用的逗号、分号和冒号
举例：By Jan 2,2000, the so-called Y2K problem was already widely considered a joke—although the reason for the non-event was the huge corporate and governmental investment in prior countermeasures.
这里的破折号与逗号都可行，破折号更好一些。
作用2、to separate an appositive from an item in a list
My three best friends—Danny, Jimmy, and Joey—and I went skiing.
Danny, Jimmy, and Joey是friends的同位语，如果用逗号的话则best friends, Danny, Jimmy, and Joey and I 一共是7个人了。
作用3、使用破折号来强调和解释句子前面的部分内容。与冒号不同，破折号做解释的作用时不必非要在需要解释的句子前面。
Post-MBA compensation for investment bankers tends to surge far ahead of that for management consultants-by tens, if not hundreds, of thousands of dollars a year.
By tens, if not hundreds, of thousands of dollars a year是解释far ahead of的，但是并没有紧跟其后。如果是冒号则必须紧跟其后。
三、 数量词
英文语法中关于表达数量的词汇需要遵循非常严格的规定：
原则1、可数名词与不可数名词
可数名词：如hat(s), feeling(s), person/people.
不可数名词：如patience, water, furniture
修饰可数名词的形容词:
Many, not many, few, fewer, fewest, number of
Fewer than, numerous, more numerous
修饰不可数名词的形容词：much, not much, little, less, least, amount of, less than a certain amount of, great, greater
More, most, enough, all 既可以修饰可数名词也可以修饰不可数名词。
注意：less 不可以修饰可数名词，只能修饰不可数名词。
There were fewer numidian Kings than Roman emperors. (correct)
值得关注的是单位（UNIT NOUNS）单词的用法
e.g. dollars or gallons
从单位单词本质上讲，他们都是可数的：one dollar, two dollars.因此，他们可与大多数可数名词修饰词连在一起。然而，单位名词代表不可数的数量:money, volume. 不可以计算MONEY的数量（也就是说MONEY这个名词是不可数名词），比如：one money, two money. 因此， 我们使用less来形容单位名词来表达underlying quantity.
Correct: we have less than twenty dollars.
We have fewer than twenty dollars: 含义是 fewer than twenty dollar bills to make the point even clearer.
原则2、两个词比较和三个词比较
比较2个事物时用形容词或副词的比较级，比较3个或以上事物时用形容词或副词的最高级。两个事务比较用between, 三个及以上用among.
原则3、number的各类用法
1. the number of:单数名词：XX的数字
the number of dogs is greater than the number of cats.
2.a number of :形容词，表示很多，大量，后加可数名词的复数形式
A number of dogs are chasing away the cats.
3.the numbers of :几乎永远是错的，必须用the number of…
4. numbers有时是正确的：
The rare Montauk beaked griffin is not extinct; its numbers are now suspected to be much greater than before.
值得注意的是：在比较数字的大小时用greater than,而不是more than
因为more than might imply that the quantity of numbers is larger, not the numbers themselves.
5.increase and decrease; greater and less
increase and decrease是表示一个事物的变化，增加或降低
greater and less 是两个事物的比较
The price of silver increased by ten dollars.(一个事物的变化)
The price of silver is five dollars greater than the price of copper.（两个事物的比较）
注意多余的情况发生，（redundancy）
The price of silver fell by a more than 35% decrease.(多余)
The price of silver decreased by more than 35%.(correct)
第十一章 平行（高阶）
GMAT偏爱简洁原则，但是这个原则却不能过度使用，还是在看句意---语法都正确的基础上考虑简洁原则。
句意是最最最重要的，因为SC的原则是不能随便更改作者的原意。也就是说如果SC的首句在句意上没有错误，那么就不能随意更换成其他句子。那么，最难的就是找出什么才是作者想表达的句子含义。
In fact, GMAT will often make the less concise answer correct by putting a subtle error into the more concise choices.
重要原则：V-A-N原则
动词 优于 形容词，形容词 优于 名词。
一个词其动词形式，形容词形式和名词形式在 含义上是有区别的，所以，最终那个受偏爱使用的词肯定是最准确表达作者含义的词。
这个问题是很多难题的关键点，什么才是作者的意图，什么形式的词更准确的表达作者的意图，不仅要看句子含义，更要仔细，细心研究和体会一个词不同形式的含义区别。
原则1、动词优于行动名词
An action noun, such as revolution, is a noun that expresses an action.
Rules apply to them.(correct) They are subject to the applicability of rules.
这个原则要灵活使用，不能一概使用，a difference among answer choices involving concision also hinges on other issues.
原则2、prefer to a that-clause(with verbs) to a series of phrases (with nouns)
The hypothesis that the universe is largely composed of dark energy seems strange.
经常使用that-clause的表达idea的词汇有： hypothesis, idea, suggestion, belief, discovery, evidence, indication, report.
The belief that the Earth is flat is contradicted by evidence that the Earth is round and the discovery that the Earth circles the Sun.
原则3、prefer a Verb to an Adjective
尽量使用动作的动词形式，而不是动词的形容词形式to be
This rash is aggravating to the pain. (wordy)
This rash aggravates the pain.(correct)
We are able to go to the store now.(wordy)
We can go to the store now.(correct)
原则4、prefer an adjective to a noun
To describe a noun or noun phrase, use an adjective and avoid the noun derived from that adjective if you can.
She has the ability to juggle.(wordy)
She is able to juggle.(better)
值得注意的是：即使一个单词的不同形式在含义上也有差异，所以要以句义为第一考量，比如：in isolation 与isolated 在含义上不同。
原则5、prefer an adverb to a prepositional phrase
To modify a verb phrase, use a simple adverb rather than a long prepositional phrase that means the same thing.
Considerably 优于 to a considerable extent.
需要注意哪怕是一个小小词的差异：
Prices at the gasoline pump have not fallen to a comparably extent.
Prices at the gasoline pump have not fallen comparably.
这里，不仅仅是to a comparably extent与fallen comparably的区别，而是fall to与fall的区别。
Fall to: the level to which something falls, rather than the extent: Prices have fallen to under a dollar.
其他值得注意的原则包括：ELIMINATION BE
Get rid of any unnecessary uses of be (be的形式包括am, are, been, is, was, were)
原则6、prefer an adjective to an adjective phrase
In particular, if the main clause contains be as well, try to the adjective alone.
This principle works similarly with nouns that identify or describe other noun.
e.g. Joan, who is a firefighter, works in York Park. (wordy)
Joan, a firefighter, works in York Park.(better)
需要注意的是以上全部都是一个PATTERN, 所有的例子在语法上都是正确的且在含义上都是明确的。
原则7、remove IT IS…THAT…
上述句式在语法上是正确的，表示强调。只是GMAT不太喜欢而已。
上述原则只是一个偏好而已，不是RULES.
有时GMAT会故意设计一些短的句子来迷惑，也许你认为GMAT偏好简约，所以就选了那个最短的句子，但是实际上也许长的句子才是正确答案。所以，看到BEING，THE FACT THAT并不说明该句子是错误的，一定要看整个句子的句义和语法。永远，简约原则都是最后考虑的。
简约：不是过短
注意False concision
原则1、keep the 介词短语（必要）
A noun adj is a noun that is placed in front of another noun that functions as an adj.
E.g. a wall of stone-----a stone wall (stone is a noun adj)
Noun adj 只在介词是of时才有用
当介词不是of时，则不能将介词短语拆掉
I talked to the Boston soldier.（too short）
I talked to the soldier from Boston. (correct)
因为这里的介词不是of, Boston 与soldier 不是介词OF连接的，所以不能将boston直接放在soldier前面。
Notice that places or locations rarely work well as Noun-adjective, unless the original prepositional phrase begins with of.
E.g. salt from the Aegean Sea Aegean Sea salt （too short）
Ore from the Ural Mountains Ural Mountain Ore (too short)
Access to the Danube River Danube River Access （too short）
Changes in the population of honeybees population Changes of honeybees (too short)
Of介词结构在表达time, period, quantity, measurement 时不能用将该名词变成形容词的方式
Memorial day week the week of memorial day
The merger year the year of the merger
The oxygen amount the amount of oxygen
The honeybee population density the density of the honeybee population
Memorial day’s week (wrong)
The honeybee population’s density (wrong)
原则2、keep that of or those of if you need to
The face I see in ads every day is that of a famous actor.
Gmat时有insert an unnecessary that of or those of, which you do have to remove.
The fields I most enjoy studying are those of physics and chemistry. Those of 多余。
原则3、keep that after a reporting verb
Reporting verb: indicate, claim, contend, report , agree, declare, reveal, rule, show, announce, assert, believe, confess, demonstrate, doubt, expect, hold, mention, observe, proclaim, reason, recognize, repeat, state, think, warn, be convinced, be certain, be assured等这些词的后面要加THAT
An article indicated that he mine was worthless.
This story shows that crime does not pay.
例外say
The water was so cold that people said polar bears would shiver.
平行结构：
Concrete nouns and action nouns
实意名词：people, places, time period or certain events
动作名词：从动词演变而来的名词：eruption, pollution, withdrawal
原则1、Concrete nouns and action nouns从来不平行
动名词：
简单动名词：tracking nouns on the outside, verbs on the inside
简单动名词的实质还是动词，也就是说简单动名词强调的是动作，而不是名词。这点可以用来辨别到底是用简单动名词还是复杂动名词还是action nouns.
Tracking satellites accurately is important for the space agency.
Something is important for the space agency.
什么是space agency 最重要的呢？
Tracking satellites，强调的是tracking的动作过程。
复杂动名词： （不）定冠词或形容词+简单动名词=复杂动名词
并与在OF介词之后，或者在ing之前
the running of marathons
marathon running
原则2、只有复杂动名词可以与action nouns平行，简单动名词不与复杂动名词平行。（GMAT严格遵守这样的规定）
I enjoyed drinking the water and tasting the wine.（wrong）
Drinking the water 简单动名词
The tasting the wine 复杂动名词
复杂动名词更接近名词的含义。
The rebels demanded the withdrawal of government forces from disputed regions, significant reductions in overall troop levels, the raising of the rebel flag on holidays, and a general pardon.
In any list of action nouns, always choose the complex gerund (often with articles and the word of) over the simple gerund phrase!
值得注意的是：如果英文单词中已经有合适的action nouns, 则不需再创造出复杂动名词。
e.g. withdrawal release已经存在，就不能用withdrawing, releasing
这类的错误在实际考试中经常出现。
总结一下：(1)concrete nouns----concrete nouns
(2)action nouns------complex nouns
(3)simple gerunds----simple gerunds.
其他也需要遵守平行原则词：
1. working verbs
只有working verbs才能与working verbs平行
The plant both exceeded output targets and ran more smoothly than ever.
Exceeded, ran是working verb
2. infinitives
不定式与不定式平行。不定式中的to可以在第二个及其之后的不定式中省略，除非在第一个不定式前面有平行的标志词。
It is critical to suspend activities, to notify investors, and say nothing.
前面已经有不定式平行提示词，所以and后的say不能省略to
It is critical to suspend activities, notify investors, and say nothing.
It is critical to suspend activities, to notify investors, and to say nothing.
It is critical either to suspend activities or to notify investors.
后面4个句子都是正确的，因为他们都遵循了上面的省略原则。
3. adj, past participles, and present participles (used as adj)
形容词、现在分词和过去分词（做形容词含义）修饰名词或代词时，他们是平行的。
A mastodon carcass, thawed only once and still fresh, is no display.
Thawed 是过去分词做定语，与fresh平行。
这个原则和用法在实际考试中经常出现，要记住他们都是形容词时是平行的
4. clauses
Only clauses starting with the same word should be made parallel. In general, clauses should not be made parallel to anything besides another clause.
从句只能和从句平行，且只能和用一个单词开头的从句平行。
A mastodon carcass, which has been thawed only once and which is still fresh, is on display. (correct)
小结：其他需要注意平行关系的：
Working verbs,
Infinites,
Adj and participles
Clauses.
第十二章 代词、修饰语（高级）
一、 其它代词
There:副词，意思是in that place，there经常被当作是一个代词，其先行词往往是一个介词短语，必须是一个名词，不能是形容词
Wrong: At current prices, Antarctic oil may be worth drilling for, if wells can be dug there and environment concerns addressed.
这里Antarctic是一个形容词，所以这里的there是错误的用法。
Right: At current prices, oil in Antarctic may be worth drilling for, if wells can be dug there and environment concerns addressed.
另外一个正确的用法是：There is a cat in a tree or there are roses on my doorstep.
Itself, themselves, one another, each other
Itself, themselves are used as objects to refer directly back to the subject:指的是自己。
The panda groomed itself.
After the agreement surfaced, the commission dissolved it.
It指的是agreement.
After the agreement surfaced, the commission dissolved itself.
itself指的是commission.
The commission itself was wrong.
one another, each other are indicated interaction between parties.
与themselves不能相互代替
The guests at the party interacted with one another.
Such and other(another)
Such: like the antecedent
The words such and other (another) often combine with a general noun to indicate an antecedent.
E.g. After the land-use agreement surfaced, the commission decided to subject any such contracts to debate in the future.
E.g. After the land-use agreement surfaced, the commission decided to subject any other contracts to debate in the future.
在上面的句子中，such指的是一种type的合同，other, another指的是additional of the same type,虽然不是exactly alike.
One
One indicates an indefinite copy or a single, indefinite part of a collection.
After walking by the chocolates so many times, Roger finally had to eat ONE.
ONE泛指巧克力，并不一定是前文中出现的巧克力。
After walking by the chocolates so many times, Roger finally had to eat them.
Them, it , they indicate definite selection of an entire object or collection.
After walking by the chocolates so many times, Roger finally had to eat one. It was delicious, but he could eat only half of it.
Do so vs do it
Do so:指的是前面一整个动作，包括动词，宾语和修饰语。
He did not eat dinner quickly, but her brother did so.
Did so指的是eat dinner quickly.
有时可以省略so
He did not eat dinner quickly, but his brother did.
与之对比，it must refer to an actual noun antecedent.
He failed to do the homework, but his brother did it.
It的用法
It是形式主语或形式宾语，Placeholder it,这时it没有先行词
3种情况：
(1)It is futile to resist temptation.
It 代表不定时宾语
(2)It gave us encouragement that we scored at all.
It 代表that从句
但有时it不能代表that从句，也就是说那个比较别扭的句子是正确的，这一点上可以参考OG里的一个句子。
It cannot normally refer to a clause under other circumstances.
(3) She made it possible for us to attend the movie.
She made possible our attendance at the movie.
She made our attendance at the movie possible.
在PLACEHOLDER情况下，it没有先行词。
避免代词在一起
由于代词经常引来歧义或混乱，所以为了清晰的句意，我们通常习惯eliminate pronouns.
After roasting the deer, the hunter extinguished the fire and then searched for a tree to hang it from.
这里的it容易引起歧义。
我们可以重复先行词来使得句子变得清晰
After roasting the deer, the hunter extinguished the fire and then searched for a tree to hang the deer from.
这时，我们可以use a generic synonym for the antecedent than to repeat the noun exactly. The synonym is often more general than the antecedent, which refers to an example of the generic synonym.
E.g. New nano-papers incorporate fibers that give these materials strength.
After the land-use agreement surfaced, the commission decided to subject any such contracts to debate in the future.
有时可以用the来代替these or such.
After roasting the deer, the hunter extinguished the fire and then searched for a tree to hang the meat from.
代词的一些使用原则：
最重要的原则是数量和性别上的一致，这些决定了哪个是合理的先行词。
1. Number:
2. Gender:
3. Repeat:
4. Proximity;
5. Case:
有时，what might seem to be slight antecedent ambiguity may in fact be tolerated.
修饰语：TOUCH RULE的例外
修饰语一般要遵守TOUCH原则，但有例外：
例外一、a mission-critical modifier falls between
通常是of介词结构(a mission-critical modifier)修饰一个名词。OF介词结构是他所修饰的名词的必要的组成部分，所以，THAT定语结构修饰的是名词+OF介词结构，而不是OF结构中的名词。
E.G. He had a way of dodging opponents that impressed the scouts.
Of dodging opponents 修饰a way, that修饰的是a way of dodging opponents,而不是opponents.
Wrong: He had a way that impressed the scouts of dodging opponents.
Best: His way of dodging opponents impressed the scouts.
e.g. An ice sheet covers 80% of the surface of Greenland, an area roughly the size of Alaska.
an area roughly the size of Alaska是修饰80 percent of the surface of Greenland, 而不是Greenland. 因为没有a mission-critical modifier“of the surface of Greenland”,则上面的句子没有被定义清楚。
例外二、a very short predicate falls between, shifting a very long modifier back.
E.g. A new CEO has been hired who will transform the company by decentralizing authority to various division heads while increasing their accountability through the use of public scorecards.
Who引导的定语从句修饰a new CEO,但是，他违背了TOUCH原则，因为如果将who引导的定语从句紧跟a new ceo的话则该句子的谓语has been hired将被挪到句子的最后，是非常捏牛的，所以，这样的句型是正确的，尽管违背了TOUCH原则。
例外三、a short non-essential phrase intervenes and is set off by commas
Our system of Presidential elections favors states, such as Delaware, that by population are over-represented in the Electoral College.
Such as Delaware是一个短短的插入语，插入在states与修饰语that by population are over-represented….之间，因为插入语比较短小，所以，这样的插入语是可以接受的。
例外四、the modifier is part of a series of parallel modifiers, one of which touches the noun.
E.g. In heraldry, the term “tincture” refers to a color emblazoned on a coat of arms and labeled with a special French word.
Emblazoned on a coat of arms and labeled with a special French word都是修饰名词a color的，所以即使第二个修饰语没有紧跟a color，但是由于他们是并列结构，所以也是可以接受的。
所有格形式
不要使用y of x’s的表达形式，要用y of x 或者x’y的表达方式。
e.g. The orca, a relative of the blue whale, is found throughout the globe.(correct)
The orca, a relative of the blue whale’s, is found throughout the globe. (wrong)
尽量避免答案中出现复数名词’s名词的表达方式。
e.g. Certain humans’ parasites have been shown to provide bacterial resistance and protection against auto-immune disorders. (wrong)
Certain parasites in humans have been shown to provide bacterial resistance and protection against auto-immune disorder.(right)
正确的句子中certain很明确的修饰parasites, 而错误的句子中certain或许修饰humans, 或许修饰parasites.
不要只是很盲目地选择不选复数名词所有格。The GMAT may force you to choose a plural possessive in the right answer.
Subgroup modifiers
如果要修饰一个大的部分中的一个小的部分，则修饰的方式如下：
1. This model explains all known subatomic particles, some of which were only recently discovered.
2. This model explains all known subatomic particles, some of them only recently discovered.
3. This model explains all known subatomic particles, some only recently discovered.
注意只有which句型中使用了working verb (were)
在some的位置，可以用any, none, all, more, most， many, each, either, neither, half, one等来代替。
定语从句vs分词（考试的重点）
在很多时候，定语从句可以和分词（当充当定语时）互换， The man who is cleaning the steps is my uncle.
The man cleaning the steps is my uncle.
但是他们在语义上有明显的区别,如:
The rate of language extinction is accelerating, a tendency ultimately culminating in the survival of just a few languages, according to some. (wrong)
The rate of language extinction is accelerating, a tendency that will ultimately culminate in the survival of just a few languages, according to some.(correct)
这是正确的句子，因为ultimately的含义是终将，所以有个将来时的含义在里面，所以，要用定语从句。
Present participles get their tense from the main verb in the sentence.
I saw a man cleaning the steps.
I see a man cleaning the steps.
I will see a man cleaning the steps.
上述句子中，cleaning与see都是同时发生的，无论是在过去，现在还是将来。如果clean与see不是在同一时间发生，则要使用定语从句，而不是分词。
I see the man cleaning the steps yesterday. (wrong)
I see the man who cleaned the steps yesterday. (correct)
独立主格
独立主格的作用：modify the main clause in some way.
独立主格的组成方式：名词+名词修饰语
独立主格的性质：sophisticated modifier
His head held high, Owen walked out of the store.
His head held high来修饰Owen如何walked out的,所以是个verb modifier.
我们也可以将同位语放在句子的结尾，前面加with
Owen walked out the store, his head held high.
Owen walked out of the store with his head held high.
Scientists have found high levels of iridium in certain geological formations around the world, results that suggest the cataclysmic impact of a meteor millions of years ago.
results that suggest the cataclysmic impact of a meteor millions of years ago. 是个一个同位语，修饰前面一个句子。
Scientists have found high levels of iridium in certain geological formations around the world. These results suggest the cataclysmic impact of a meteor millions of years ago.
GMATD的句子改错题永远不可能看到两个分开的句子，但是这里可以看出独立主格如何联系两句话的，记住，永远不要用which来连接。
Scientists have found high levels of iridium in certain geological formations around the world, which suggests the cataclysmic impact of a meteor millions of years ago. (wrong)
Scientists have found high levels of iridium in certain geological formations around the world, and this suggests the cataclysmic impact of a meteor millions of years ago. (wrong)
GMAT不喜欢单独用this or that,因为他们容易引起歧义。
现在分词结构可以用来表示前面一句话的影响或结果：
Scientists have found high levels of iridium in certain geological formations around the world, suggesting the cataclysmic impact of a meteor millions of years ago.(correct)
In some cases, you can use an –ing form (with a comma) in place of an absolute phrase. At the end of a sentence, either an –ing form or an absolute phrase can indicate a result of the preceding clause.
An absolute phrase is typically separately from the rest of the sentence by a comma. However, for an absolute phrase at the end of a sentence, you may also use a dash(-)。
第十三章 动词与对比(高级)
不定时
不定式可以做名词、形容词或副词
名词: I love to swim:名词，to swim做love的宾语
形容词：The person to meet is here. To meet是修饰名词person
副词：Sue paused to eat lunch. To eat修饰动词paused
也可以说：Sue paused in order to eat lunch.
在使用in order to时应注意不定时的目的。
The contractor demolished the building to keep it from falling down accidently.
主语是the contractor,同时也是to keep的主语，表达了demolish 的目的。It 指的是the building.
The building was demolished to avoid falling down accidently.
主语是building,同时也是不定时to avoid 的主语，然而a building 不能主动的avoid，所以上面的句子错误。
虽然不定时可以做名词，但是它不是noun-like structure.
不定时虽然可以做宾语，但是并不能像修饰名词一样修饰不定时。
现在分词
现在分词比不定时更像一个名词，可以做动词的主语、动词的宾语和介词的宾语。
做动词的主语：swimming is fun
做动词的谓语：I love swimming
做介词的宾语：I dream of swimming
简单动名词：eating apples quickly (更像动词)
复杂动名词：The quick eating of apples (更像名词)
AGAIN:复杂动名词和简单动名词不平行，有action noun时不用复杂动名词
动名词前面的所有格：如果动名词有个DOER,则需要加有所格形式
注意该动名词是主语。-ing form function as a noun.
E.g. Mike’s swimming is the product of new coaching techniques.
Mike’s behavior 是重点
Mike swimming is the product of new coaching techniques.(wrong)
这里swimming是mike的modifier.所以mike是主语（错误）
因此，必须确定-ing form是修饰语还是主语。
Right: I like Mike’s swimming(喜欢的是swimming)
Right: Mike swimming is a sight to be hehold.(Mike himself can be the sight)
Right: Mike’s swimming is a sight to behold.(the swimming can be the sight)
原则是尽量不是用动名词的所有格形式，如果需要所有格，就用action noun的所有格，如果一定要所有格中出现动名词，则用its, their, his or her.
分词
现在分词和过去分词可以用来当modifier.
-ing form的四种用法：
Verb (进行时态) she is fixing the faucet.
Noun(动名词) fixing the faucet is not fun.
Adj(现在分词) the person fixing the faucet is tired.
Adv(现在分词) she crouched under the sink, fixing the faucet.
过去分词充当完成时态动词或形容词
Verb(过去分词) she has broken the lamp
Adj(形容词) the broken lamp is on the stairs.
VERBAL OR VERB的使用
现在分词：表达一种结果result，与intention 无关
Investors sold the stock rapidly, causing panic.
不定式：表达一种意愿，intention, 与结果无关result.
Investors sold the stock rapidly to cause panic.
A rule of thumb: water droplets freeze to form snow is acceptable, although there is no intention.
重点中的重点：使用现在分词、从句和不定式做modifier的含义上的区别
现在分词：A technique alleviating pain is growing popular.
从句： A technique that alleviates pain is growing popular.
上面的两个句子中现在分词和从句都是修饰主语a technique的，a technique是alleviate 的implied subject.
不定式：A technique to alleviate pain is growing popular.
This sentence means that you (or someone else) can alleviate pain by means of this technique. In other words, technique is not meant to be the subject of the action alleviate.
Often, when you modify a noun with an infinitive, that noun is not the implied subject of the infinitive.
There is a book to read.
The book will not read, someone will read the book.
A plan conquering the world is in his files.(unlikely)
A plan that will conquer the world is in his files.(unlikely)
A plan to conquer the world is in his files. (probably)
A plan is a means by which someone can conquer or will try to conquer the world.
It is unlikely that the plan itself is actually conquering the world or will conquer the world. Thus, we should use the infinitive.
引申：在实际考试中，出现了不定式、that从句和分词做modifier，不知道该怎么选，可以根据上述原则选择，infinitive的主语不是原句子中的implied subject,而是someone，所以如果分析认为句子的主语不是不定式的主语时可以选择不定式，否则选择分词或that从句。
Like and as
Like:介词，含义是：similar to , in a manner similar to
后面跟名词、代词、可以修饰名词或动词
Like的位置变化会给句子的意思带来不同：
Like you, I danced last night:像你一样，我昨天晚上也跳舞了。这里的含义是“你”昨天晚上跳舞了， 我和你一样。
I danced like you last night: 我昨天晚上像你一样跳舞。（含义是我昨天晚上跳舞了，但不一定“你”昨天晚上也跳舞了，只是我跳舞跳得像“你”一样）应该注意这里的含义上的区别。
此外, like对比有暗喻的含义：he ran like the wind.并不是说风也会跑，而是风刮的快的意思。
(1)I want to coach divers like Grey Louganis.
=I want to coach divers who are like Grey Louganis.
Or
=I want to coach divers in the same way as Grey Louganis does.
(2)I want to coach divers, like Grey Louganis.
=like Grey Louganis, I want to coach divers.
Unlike的用法与like的用法一样。
Unlike you, I danced last night.
Most materials under a wide range of conditions resist the flow of electric current to some degree, unlike superconductors, which demonstrate zero electrical resistance.
As连词或介词
用法：
（1） duration As: As I strolled to the store, I smelled the air.(while, during)
（2） causation As: I will not tell you, as you already know.(since, because)
（3） comparison As: You should walk As she wants you to.(in the same way)
As是最重要的表示对比的连词，有时可以与just, so, or even so too一起使用。
Just as the trains were late yesterday, the buses are late today.
Just as the trains were late yesterday, so too are they late today.
As can also appear with a phrase, rather than full clause.
As in the previous case, the judge took an early break.
介词as 可以作为名词或名词短语：用法有3种：
Function as: As your leader, I am in charge.(in the role of)
Equation as: I think of you as my friend.(you are my friend)
Stage as: As a child, I thought I could fly.(when I was)
仔细体会以下as, like的含义：
I will jump up like a clown.(in a clownish manner)
I will jump up as a clown.(in a clown suit)
I will jump up as a clown might.(like a hypothetical clown)
I will jump up as a clown.(in a clown suit)
As…as…对比含义，第一as后是形容词和副词，第二个as后可以是名词、短语或甚至一个从句
They are as hungry as you.
They are hungry as you are.
They are as hungry as they were last night.
GMAT中的LIKE 没有举例的含义，一定要注意啊！use such as instead.
比较中的数字
（1） 倍数的比较，使用as…as….
The man is five times as old as his grandson.(correct)
The man is five times older than his grandson.(wrong)
不能将倍数与比较级相联系
Og中的错误:5 times greater than…. 应该避免这样的用法
The cost of a ticket is 12, six times the cost ten years ago.(correct)
The concert was attended by 300 people, twice the previous attendance. (correct)
(2) 加或减的比较的，使用more than or less than
I am ten years older than you.(correct)
I am ten years as old as you。（wrong）
More or less的用法
I own more than I should.(名词或代词)
I own more shirts than I should.(形容词)
I sleep more than I should.(副词)
High, low, higher, lower只能当形容词
My bills are lower than they were last year. (correct)
I spend less than I did last year. (correct)
I spend lower than I did last year.(wrong)
其他比较结构
注意more, less的位置，有时会引起歧义
We have even more efficient engines than before. (more可以修饰efficient，也可以修饰engines, 所以有歧义)
We have even more engines that are efficient than before.（more modify engines）
We have engines even more efficient than before. (more modify efficient)
Exceed, surpass可以表示比较
The incidence of the disease among men EXCEEDS the incidence among women.
The incidence of the disease among men EXCEEDS its incidence among women.
The incidence of the disease among men EXCEEDS that among women.
In addition to 的用法：
后面可以加其他东西(another example to a different noun)，也可以同类东西(add another example)
In addition to taxes, death is inevitable.
In addition to Munster cheese, I like Swiss.
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