说明：
本文是在国内GMAT考生中广为流传的PREP语法笔记整理而成。这些PREP题目，包括了老PREP和新PREP中的各2套共493道题目。我们把这些题目，按20道题目一组，创建了25个练习册，方便大家先做后看。
注意：此部分解析为非官方、非专业老师整理的解析。
201. (GWD30-Q4)
The three women, liberal activists who strongly support legislation in favor of civil rights and environmental protection, have consistently received labor's unqualifying support.
A. have consistently received labor's unqualifying support
B. are consistently receiving the unqualifying support of labor
C. have consistently received the unqualified support of labor
D. receive consistent and unqualified support by labor
E. are receiving consistent and unqualified support by labor
题目释义：The three women, …, have consistently received….
考点：
1. by someone修饰的动词，所以不能receive support by labor
2. support作为n.时的固定搭配：
(have/receive/win) support of/from someone 来自某人的支持
support for something/someone 支持某事/某人
in support of something 支持某事
3. unqualifying与unqualified(from manhattan)
unqualifying释义: not meeting some sort of standard for qualification
unqualified释义: without any sort of restriction or reservation
4. 关于时态使用：除非1.原句有明显的动词时态和状语搭配错误。（比如用过去时修饰NEVER,用完成时修饰YESTERDAY）2.原句有明显的语法问题，而语法正确答案之中，没有和原句一致的时态；其他情况，慎重修改原句时态。另外，现在完成时态，一般不需要明显的时间词就可以使用，因为它所隐含的时间是现在now.
选项分析：
A. unqualifying使没有资格的，意思不对，应该用unqualified绝对的(used for emphasizing that a quality is complete and total)，记住unqualified support常用表达。N’s n或n of N，都可以，能表达清楚意思又简洁的为上，这里labor’s后面已经有一个unqualified这种不是专门为了组成名词短语而存在的形容词（如vocal tract）了，所以还是用n of N比较清晰。
B. are consistently receiving不能算错，只是其和原句have consistently received的时态不符，一般没有特殊原因不改变原句的逻辑意思，时态等，除非有很明显的标志，有必改不可的原因；unqualifying错误。
C. correct；A,B根据unqualifying排除；D,E根据support by labor排除(by sb.修饰的是动词)；support of/from someone正确搭配
D. 用一般现在时也是合理的，时态没有问题；错误的用consistent修饰support改变原句含义；receive support by labor错误，正确搭配是support of/from labor
E. 用consistent修饰support改变原句含义；receive support by labor错误
补充说明：
Prep08版着实有几个地方强调不更改A句的含义，基本可以有这样的结论：如果A句逻辑含义合理，则没有特殊原因(比如与A句逻辑含义相同的选项都有明显错误)，那么就不可以随意更改句意。
202. (GWD-27-Q7)
Providing initial evidence that airports are a larger source of pollution than they were once believed to be, environmentalists in Chicago report that the total amount of pollutant emitted annually by vehicles at O’Hare International Airport is twice as much as that which is being emitted annually by all motor vehicles in the Chicago metropolitan area.
A. as much as that which is being emitted annually by all
B. as much annually as is emitted by the
C. as much compared to what is annually emitted by all
D. that emitted annually by all
E. that emitted annually compared to the
题目释义：Providing initial evidence..., environmentalists…the total amount of pollutant emitted annually by vehicles at O’Hare International Airport is twice….
考点：
1. 比较结构
2. 倍数表达：twice (as much as) sth.; X times adj. than; X times as adj. as; double sth.
3. as,than可以做比较从句的主语，例：
In one of the bloodiest battles of the Civil War, fought at Sharpsburg, Maryland, on September 17, 1862, four times as many Americans were killed as would later be killed on the beaches of Normandy during D-Day. As指代了americans。
选项分析：
A．is being错误，且as可以做比较从句的主语，删去being后可以直接用as much as is emitted annually；但是即便如此amount X is twice as much as amount Y也不如直接twice amount Y简洁
B．annually位置错误，应该放在is emitted后面修饰emitted
C．as…compared to搭配错误；what is annually emitted by all中what的范围大于the total amount of pollutant，而且其实可以简化
D． Correct；twice后面可以直接接名词，twice as much as也是对的
E． compared to多余，且compared to的比较两端不平行，一边是pollutants，一边是motor vehicles
203. (T-4-Q29)
In late 1997, the chambers inside the pyramid of the Pharaoh Menkaure at Giza were closed to visitors for cleaning and repair due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing and fungus was growing on the walls.
A. due to moisture exhaled by tourists, which raised its humidity to such levels so that salt from the stone was crystallizing
B. due to moisture that tourists had exhaled, thereby raising its humidity to such levels that salt from the stone would crystallize
C. because tourists were exhaling moisture, which had raised the humidity within them to levels such that salt from the stone would crystallize
D. because of moisture that was exhaled by tourists raising the humidity within them to levels so high as to make the salt from the stone crystallize
E. because moisture exhaled by tourists had raised the humidity within them to such levels that salt from the stone was crystallizing
题目释义：C…were closed….because moisture had raised the humidity… to such levels that…
考点：
1. Because of 后只能加简单的名词结构，because of sb’s doing 一定要改成because
这种情况同样适用于due to， despite（in despite of）， as a result of
2. 代词指代
3. Such/so…that固定搭配。Such … so that搭配错误。
选项分析：
A. due to moisture无法表达closed for cleaning and repair的直接原因；用which引导非限定性定从不能表达出该有的意思；such…so that固定习语使用错误；its无所指代。
B. due to moisture无法表达closed for cleaning and repair的直接原因。thereby raising用法awkward；its无所指；such that + would(情态动词)是表达目的，逻辑含义错误；stone would crystallize和fungus was growing on the walls不平行。
C. tourists were exhaling moisture无法表达closed for cleaning and repair的直接原因；Which在GMAT里面不可以指代前面整个分句（至今没有一道官方题目有which指代前面整句）；Such that + would(情态动词)是表达目的，逻辑含义错误；them指代了tourists错误；stone would crystallize和fungus was growing on the walls不平行。
D. because of moisture无法表达closed for cleaning and repair的直接原因；so … as to make使得与后面的fungus was growing on the walls不平行； that was exhaled没有必要补出that was，累赘。
E. Correct. humidity within them...tourists身体里面不可能包含有humidity，而且by tourists在从句的介宾短语里，是不会被指代的，所以them不会指代混乱。
补充说明：
根据逻辑含义本题可以迅速得出选项：
首先were closed to visitors for cleaning and repair的原因，只有一个，就是“潮气引发了什么”而使得它需要修理了，只有E表达了这个意思，其他选项，看前三个词，就可以排除。A,B,D表达的是，是因为“潮气”本身，使得他们要修。C表达的是，旅客们呼出潮气，所以他们要关闭整修，也是不对的。只有E，表达出了潮气引起了湿度上升，所以chambers要关闭整修。
204. (T-9-Q16) (OG12-53)
The nineteenth-century chemist Humphry Davy presented the results of his early experiments in his “Essay on Heat and Light,” a critique of all chemistry since Robert Boyle as well as a vision of a new chemistry that Davy hoped to found.
A. a critique of all chemistry since Robert Boyle as well as a vision of a
B. a critique of all chemistry following Robert Boyle and also his envisioning of a
C. a critique of all chemistry after Robert Boyle and envisioning as well
D. critiquing all chemistry from Robert Boyle forward and also a vision of
E. critiquing all the chemistry done since Robert Boyle as well as his own envisioning of
题目释义： “essay on heat and light”，a critique of…as well as a vision of…
考点：
句子结构（grammatical construction） 平行结构（parallelism） 逻辑意思（logical predication）
1. 同位语
同位语结构的形式: (参考白勇语法)
1) 名词性同位语, 名词解释名词:
n. , n. ; n. , a/an + n.或 a/an + n. , n.
2) that引导同位语结构:
抽象名词(evidence, result, principle等等) + that从句, that从句对抽象名词进行具体化解释
3) 概括性同位语结构:
用一个概括性的名词去概括前面的解释对象;短语/句子, a program/ an advance/ a practice that…
4) 名词重复性同位语结构:
n. , n.(重复所修饰的名词) + that…或 n. , the same n.(重复所修饰的名词) that…
2. as well as前后对称，并且应当注意的是在A as well as B的用法中，强调的是A。
选项分析：
A. correct；a critique是“essay on heat and light”的同位语；a critique和a vision在as well as前后对称
B. critique与his envisioning不平行；envisioning有具体的名词形式即vision，应直接用名词；his指代不清
C. critique与envisioning不平行；and…as well混搭累赘；envisioning有具体的名词形式即vision，应直接用名词。
D. critiquing做伴随状语修饰前面分句错误；critiquing和a vision在and also前后不对称。From…forward不简洁，不如直接用since。
E. done多余；envisioning错误同B；his own改变句意；all the chemistry和his own envisioning的对称使得Davy批判的是他自己；
OG12-53解释：
Parallelism; Rhetorical construction
The main objective of the sentence is to describe “Essay on Heat and Light” as Davy’s presentation of his own experiments and to further explain that the essay served as both a critique of previous chemistry and a vision of a new kind of chemistry. The clearest, most effective form for providing this explanation of the essay’s function is to make critique and vision both appositives of “Essay on Heat and Light,” and to present them in a parallel structure.
A. Correct. Th e phrases describing the essay’s function are presented in parallel form.
B. Critique and his envisioning are not parallel; the phrase and also his envisioning is unnecessarily wordy; it is also unclear to whom his refers.
C. The two descriptors are not parallel.
D. The two descriptors are not parallel.
E. The meaning is confused in the assertion that Davy critiqued his own vision of chemistry.
Th e correct answer is A.
205. (T-9-Q15)
The commission’s office of compliance, inspections, and investigations plans to intensify its scrutiny of stock analysts to investigate not only whether research is an independent function at brokerage firms, but also whether conflicts result when analysts own the stocks they write about or when they are paid for their work by a firm’s investment banking division.
A. to investigate not only whether research is an independent function at brokerage firms, but also whether conflicts result when analysts own the stocks they write about or when they are
B. to investigate not only whether research is an independent function at brokerage firms, but also if conflicts result when analysts own the stocks they write about or they are
C. to not only investigate whether or not research is an independent function at brokerage firms, but also if conflicts result when analysts own the stocks they write about or are
D. not only to investigate whether or not research is an independent function at brokerage firms, but also whether conflicts result when analysts own the stocks they write about or are
E. not only to investigate whether research is an independent function at brokerage firms, but also whether conflicts result when analysts own the stocks they write about or when
题目释义：The commission’s office of compliance and investigations plans to…to investigate not only whether…, but also whether… when analysts…or when they are…
考点：
平行结构（parallelism） 习惯用语（idiom）
1. not only…but also
重新摘录一下前面提到过的用法：
首先Not only…..but (also)表示的关系是递进, 其中also可以省略……….But/but also表示的是转折.
not only ...but also表示并列，不能表示转折，不要有先入为主的感觉认为not only...but also必须一起出现。单独出现but also是可能的。
1) 在正常语序中: not only … but also 应连接两个相对称的并列成分。
在正常语序中: 短语本身不可以加入其它成份，比如变成：not only...but it also...是错误的（因为破坏了平衡）。
2) not only … but also 连接两个主语时，谓语动词要和与其最近的主语保持人称和数的一致。
3) not only … but also 不能用在否定句中。
4) not only … but also 连接两个分句，并且 not only 位于句首时，第一个分句中的主语和谓语要部分倒装。
2. whether or not的使用：(见the handbook of good english)
1) 在引导宾从的时候只能够用whether，而不能加or not，否则累赘
2) 在引导状从的时候必须加上or not，即whether or not.
3. whether表示列举时候的用法：Whether A, B, or C.
选项分析：
A. correct。Not noly…but also前后对称；Whether后省略or not正确；Or前后平行对称。
B. if在书面语中不能表示“是否”，只能表示“如果”，所以应该使用whether，且not only…but also前后不对称；Or前后不对称。
C. whether or not不简洁；If错误同B；not only后面跟了动词，but also后面不对称；Or错误同B。
D. whether错误同C；or错误同B。
E. not only…but also前后不对称；or错误同B。
206. (GWD-21-Q29)
While studying the genetic makeup of corn, a new class of mutant genes was discovered by Barbara McClintock, a discovery which led to greater understanding of cell differentiation.
A. a new class of mutant genes was discovered by Barbara McClintock, a discovery which led
B. a new class of mutant genes in corn were discovered by Barbara McClintock, leading
C. Barbara McClintock discovered a new class of mutant genes, and it led
D. Barbara McClintock discovered a new class of mutant genes, a discovery that led
E. Barbara McClintock, who discovered a new class of mutant genes, leading
题目释义：while studying the genetic makeup of corn，Barbara McClintock discovered…,a discovery that led…
考点：
逻辑意思（logical predication） 句子结构（grammatical construction）
1. 状语从句的省略：
1） 两点省略要求：
第一点是毫无疑问的：逻辑主语等于句子主语
第二点也是必须的：从句的谓语必需是be（没要求主句谓语也必需是be！换句话说状从的省略可以看成是省略了一个be），且从句主语和谓语要么同省，要么同留。
2）形式
(1) 正确形式: 表示时间/条件/转折/让步的连词(when/while/if/unless/although/even though/even if) + 形容词短语/-ing短语/-ed短语
(逻辑主语等于句子主语) (所以when a child/ when children是错的； if + n.也是错的)
(2) 错误形式:表示时间/条件/转折的连词 + 介词短语/名词短语 (although just inside the orbit of Jupiter是错的)(OG10-69)
(3) 特殊情况:once可以加介词短语/名词短语; whatever可以加名词短语
2. 同位语结构
选项分析：
A. While studying状语从句的省略在句首，studying的逻辑主语为句子主语，执行studying动作的应该是人，a new class of mutant genes错误；要用that引导限制性定语从句。
B. 逻辑主语错误同A。leading在句尾做伴随结果，与主语Barbara McClintock无法搭配（虽然伴随结果状语没有逻辑，但是状语与被修饰分句主语结合有意义）。
C. It不能指代前面整句因此无指代对象，最好用同位语。
D. Correct；逻辑主语正确；A discovery作为同位语指代前句，that引导限定性定语从句修饰a discovery
E. who…genes作为插入语出现；整个句子缺少谓语动词。
207. (T-4-Q30)
Unlike the short flights of the shuttle and earlier spacecraft, which carried sufficient power in fuel cells and batteries, a permanently orbiting space station will have to generate its own electricity.
A. the short flights of the shuttle and earlier spacecraft, which carried sufficient power in fuel cells and batteries,
B. the shuttle and earlier spacecraft, with sufficient enough power in fuel cells and batteries for their short flights,
C. the short flights of the shuttle and earlier spacecraft, which enabled them to carry sufficient enough power in fuel cells and batteries,
D. the shuttle and earlier spacecraft, which were capable of carrying sufficient power in fuel cells and batteries for their short flights,
E. the flights of the shuttle and earlier spacecraft, whose shortness allowed them to carry sufficient power in fuel cells and batteries,
题目释义：Unlike the shuttle and earlier spacecraft，…., a permanently orbiting space station…
考点：
比较（comparison）
1. 比较结构双方应对等（看见是比较考点时，最重要的是找到比较对象）。
2. with结构。
3. 同义词重复。
选项分析：
A. 比较对象不对等，Unlike后的关键字是the short flights，而比较对象是a space station
B. Sufficient和enough同义词重复；With引导独立主格结构有修饰歧义
C. 比较对象错误同A；which指代的是shuttle and earlier spacecraft，它们逻辑上无法成为enable的动作发出者；them指代不清晰；sufficient和enough同义词重复
D. Correct；句子含义为shuttle和spacecraft有能力带足够完成短程飞行的power
E. 比较对象错误同A；whose指代flights，them指代不清晰；逻辑错误，并不是短程允许了他们可以带足够的power，而是他们能带足够的power来完成短程飞行
补充说明：
1. 关于夹心修饰 (by aeoluseros)：
所以歧义修饰，是因为引发了不同的理解，而并不是语法上是否会有不同的修饰，所谓夹心修饰也是这个原则。很多人对“夹心修饰”都有过一个误解，认为S, v-ing, V. + O.结构中，v-ing既可以往前修饰S，也可以往后修饰V就是夹心，而实际上夹心并不是“可以往前修饰S，也可以往后修饰V” 。在S, v-ing, V. + O.这样的表达中，v-ing约定俗成只伴随修饰动词，见下例：
prep 2-104 The yield per acre of coffee berries varies enormously, because a single tree, depending on its size and on climate and altitude, is able to produce enough berries to make between one and twelve pounds of dried beans a year.
这个句子里depending不能改为dependent，因为depending和dependent的区别在于，前者伴随修饰谓语动词is able to produce，后者则是修饰名词single tree，会造成逻辑上不对。用dependent时："依靠于size的一棵树能够长出足够的浆果"。用depending时，“一棵树取决它的size来做到长出足够的浆果”。
2. Windmaple：以下redunancy word list兼出自官方资料：
lag behind, by xx% (less)
from ... (down/up) to
rise (higher)
then .. (subsequently)
now .. (currently)
(to someone,) Paris is someone's home
enable someone to (be able to)
continue, and (have already done)
(up) until…
per capita consumption ... (per person)
each year ... (annually)
(consistently) ... doing sth.
also ... (as well)
the more ..., the more ..., become (increaseingly)
there is (continuous) sth occurring
someone is doing sth (continuously)
(so) in order to
then (later)
then (subsequently)
208. (GWD-11-40)
Scientists who studied the famous gold field known as Serra Pelada concluded that the rich lode was not produced by the accepted methods of ore formation but that swarms of microbes over millions of years concentrated the gold from jungle soils and rivers and rocks.
A. not produced by the accepted methods of ore formation but that swarms of microbes over millions of years
B. not produced by the accepted methods of ore formation but instead swarms of microbes over millions of years that
C. not produced by the accepted methods of ore formation but swarms of microbes over millions of years that
D. produced not by the accepted methods of ore formation but by swarms of microbes that over millions of years (D)
E. produced not by the accepted methods of ore formation but that swarms of microbes over millions of years
题目释义：Scientists studied the famous god filed not by…but by…
考点：
平行结构（parallelism）
1、not…but…后面要平行，如not by…but by…
选项分析：
A. not produced by…but that不平行
B. not by…but swarms搭配错误；but instead语义重复；that位置错误，使得状语over millions of years修饰对象不清
C. not by…but不平行
D. correct；Not by…but by正确
E. 错误同A
补充说明：
1. 看见这类单纯的考平行的题，可以迅速看选项选择。
2. windmaple: 如果but后面接名词是不能有instead的，因为but是介词；但是如果but后面接动词就变成了连词，中间加副词instead没问题。Prep07 1-73：Evolutionary psychology holds that the human mind is not a "blank slate" but instead comprises specialized mental mechanisms that were developed to solve specific problems human ancestors faced millions of years ago.
209. (T-3-Q7)
In Scotland, the number of wild salmon have been reduced because of uncontrolled deep-sea and coastal netting, by pollution, and by various other threats to the fish’s habitat.
A. number of wild salmon have been reduced because of uncontrolled deep-sea and coastal netting,
B. number of wild salmon is reduced because deep-sea and coastal netting is not controlled,
C. numbers of wild salmon has been reduced because of uncontrolled deep-sea and coastal netting,
D. wild salmon’s numbers are reduced by deep-sea and coastal netting that is not controlled,
E. wild salmon’s numbers have been reduced by uncontrolled deep-sea and coastal netting,
题目释义：In Scotland，wild salmon’s numbers have reduced by…by….and by…
考点：
主谓一致（agreement） 平行结构（parallelism predication） 逻辑意思（logical construction）
1. the number of+复数名词，谓语用单数；a number of +复数名词，谓语用复数。
2. and平行结构。
选项分析：
A. have错误，主谓不一致；because of 与未划线部分的by不平行
B. because与未划线部分的by不平行
C. the numbers错误(MANHATTAN SC上提到：Never select an answer choice containing the phrase THE NUMBERS OF)；and平行错误同A
D. that is not controlled不如uncontrolled简洁
E. correct；关于number与numbers无需做过多区分，只要保持主谓一致即可（有一种说法认为因为总数量的持续改变所以要用复数numbers，有一定道理，不过未经理论证实）
补充说明：
Number的用法小结—by Mayanist：
几种用法之间区别：非核心词与核心词；number的意义；number与相关成分的单复数一致关系。
1) a number of / numbers of + 可数名词复数 + 动词复数
可以理解为量词结构，a number of表示一些，numbers of表示大量
of后面的复数名词才是核心词，谓语动词因此总是复数
Many students arrived early, but only a number of them worked on their exercises.
The lake produces a good number of (=a lot of) salmon each season.
Numbers of birds fly across the lake.
另外：any number of 用于非正式场合，表示大量
There could be any number of (=many) reasons why she's late.
OG237. It seems likely that a number of astronomical phenomena, such as the formation of planetary nebulas, are caused by the interaction of two stars orbiting each other at close range.
OG152. When the technique known as gene-splicing was invented in the early 1970’s, it was feared that scientists might inadvertently create an “Andromeda strain,” a microbe never before seen on Earth that might escape from the laboratory and kill vast numbers of humans who would have no natural defenses against it.
709. The Coast Guard recently redesigned channel markers in the Chesapeake Bay to
accommodate large numbers of ospreys, whose huge nests formerly obstructed the lights.
829. The speculative fever of the Roaring Twenties infected rich and poor alike; great numbers of people were dangerously overextended, credit was absurdly easy to obtain, and most brokerage houses required only ten percent cash for stocks bought on “margin.”
2) the number of + 可数名词复数 + 动词单数: number是核心词，可以被具体的一个数字表示 可数物品累积起来的数量, 可数名词需用复数形式
这时number是核心词，可以被具体化为一个数字，如50或者100，谓语动词因此总是单数
The number of students who participated the interview was 100.
Today’s case brings the number of successful prosecutions in the region to thirty-four.
[这里有个疑问有待考证：是否可以从例子派生出The numbers of girl and boy students are respectively 30 and 70? 如果可以，则规则为：the number(s) of + n.(总是复数) + v.(单数或者复数-取决于number的形式)]。
OG-verbal-5. A Labor Department study states that the number of women employed outside the home increased by more than thirty-five percent in the past decade and accounted for more than sixty-two percent of the total growth in the civilian work force.
492. Los Angeles has a higher number of family dwellings per capita than does any other large city.
有人问为什么不选(D) higher numbers of family dwellings per capita than do other large cities（C）. ETS：the plural numbers is incorrect in that there is only a single number of such dwellings.
这题是什么时候用单数，什么时候用复数number的好例证：ETS的意思是，因为人均住房面积只用一个数值就可以表示了，例如20平方米/人，即number 就是这个数，所以number 和对应谓语动词都用单数。另外，比较级higher表示将LA的number 和其他城市相应的number相比：one number is larger/greater/higher than the other number.
3) numbers作为核心词，表示可以被具体化的几个数
530. New Jersey has one of the five highest numbers of reported（D） cases of Lyme disease in the United States.
908. Upset by the recent downturn in production numbers during the first half of the year, the board of directors, at its quarterly meeting, raised the possibility of
adding worker incentives.
因为每个公司的生产指标有很多，所以用复数形式的production numbers。比较题No.492，在那里family dwellings per capita只可以被具体化为一个数。
这些情况下，如果明确知道有多个数字，就用numbers。再例如Don't judge a team by its numbers.不能仅仅从数字（指标）上判断一个队（的好坏）。如NBA队伍中每个球员都有rebound, assist, turnover, score等指标，球队有胜率，排名等指标。这些指标就是由多个数字表达的，所以即使team是单数，但是its + numbers是最合理的。上面的句子也可以改写为：Don’t judge a team by those numbers listed on its website.
4) numbers作为核心词，但可以被具体化的几个数倾向不明显
OG-verbal-72. The gyrfalcon, an Arctic bird of prey, has survived a close brush with (A) extinction; its numbers are now five-times greater than when the use of DDT was sharply restricted in the early 1970’s.
因为动词是复数，所以可推知numbers是number的复数形式，而不是什么固定用法。
TTGWD9-Q7: In Scotland, the (E) wild salmon’s numbers have been reduced by uncontrolled deep-sea and coastal netting, by pollution, and by various other threats to the fish’s habitat.
另外，一些讨论中说：numbers是复数做“人数，鸟群”讲。Longman字典：Visitor numbers increase in the summer. 游客人数在夏季增加。现代英汉词典：Birds gather in large numbers beside the river.鸟儿一群群地聚在河边。但是显然后面一个例子中in large numbers是做副词用，参见5)。
这一类用法是最难的，还没有找到最有说服力的解释。但是作题的时候，我们可以借用其他方面的线索，排除错误项。
5) in number(s) 惯用法: 如downturn/decline in number(s)，表示在数量指标方面
In number adv., prep., n.总共，在数目上
They were printed in limited numbers.
Young people have been leaving the countryside in large numbers for urban
areas. [leave … for …]
The condors have dwindled to an estimated sixty in number.
48(non-OG). The golden crab of the Gulf of Mexico has not been fished commercially in great numbers, primarily because it lives at great depths – 2,500 to 3,000 feet down.
550. Once common throughout the Western plains, black-footed ferrets are thought to have declined in number as a result of the poisoning of prairie dogs, their prey. 这题主要是考察逻辑关系：black-footed ferrets (is) common throughout …, 只有A正确。
看来in number 或者in numbers在某些情况下，并不需要严格区分，毕竟GMAT时要求找最佳答案。或许550中用numbers也没错。
6) the number (s) of + 名词单数或者复数 + 动词单数或者复数，表示标号，数字标识
这时number是核心词，number、物品、谓语动词三者的单/复数形式要一致
The numbers of the machine parts A and B are respectively 201 and 203.
机器零件A和B的标号分别是201和203。
派生出The number of machine part A is 201.
这时number与numbers互为单复数的关系。注意，这里。
The numbers of the machine parts are not available. 这些机器零件的号码找不到了。
210. (GWD-1-Q2) 重点题
By merging its two publishing divisions, the company will increase their share of the country's $21 billion book market from 6 percent to 10 percent, a market ranging from obscure textbooks to mass-market paperbacks.
A. their share of the country's $21 billion book market from 6 percent to 10 percent, a market ranging
B. from 6 percent to 10 percent its share of the $21 billion book market in the country, which ranges
C. to 10 percent from 6 percent in their share of the $21 billion book market in the country, a market ranging
D. in its share, from 6 percent to 10 percent, of the $21 billion book market in the country, which ranges
E. to 10 percent from 6 percent its share of the country's $21 billion book market, which ranges
题目释义：the company will increase (to x from y) its share of [( ) market, (which ranges .... )]
考点：
指代一致（agreement） 逻辑意思（logical predication）
1. the company是主语，指代也用单数。
2. which的指代
选项分析：
A. their指代the company错误 。
B. which可以跳跃指代，但是此处which离其指代对象隔了一个状语in the country，而且country与ranges是gramatically matched的，故B不佳。
C. their错误同A，ranging错误同A。
D. which错误同B；of和要连接的对象离的太远不好。
E. correct；which离其指代对象比B更近，因此更好，记住选项是比出来的；to…from…结构中to 10 percent提前以示强调；逻辑上讲，一个国家的图书市场不可能只有从from obscure textbooks to mass-market paperbacks，所以which逻辑上指代its share of the country's $21 billion book market整体。
补充说明：
Which指代小结—by aeoluseros：
以下收录官方材料中能对于which的使用，可以发现which的指代其实并没有固定死规则，不一定只指代最近的名词，跟所有代词一样，有就近指代的的倾向，但是具体修饰对象，应该根据各种线索或者逻辑含义来判断：
1. 尽管A of B的结构，which没有就近修饰。
561. One pervasive theory explains the introduction of breakfast cereals in the early 1900s as a result of the growing number of automobiles, which led to a decline in horse ownership and a subsequent grain glut; by persuading people to eat what had previously been horse feed, market equilibrium was restored.
2. which不一定跳过插入语指代：
462. Judge Lois Forer’s study asks why some litigants have a preferred status over others in the use of a public resource, the courts, which in theory are available to all but in fact are unequally distributed between rich and poor.
3. 通过单复数判断which的所指：
80. Changes in sea level result not only from changes in water temperature, which affect water density, but also from the melting of glaciers.
44. The survival of coral colonies, which are composed of innumerable tiny polyps living in a symbiotic relationship with brilliantly colored algae, is being threatened, experts say, not only by pollutants such as agricultural runoff, oil slicks, and trash, but also by dropped anchors, probing divers, and global warming.
173 (GWD-10-Q18) In analyzing campaign expenditures, the media have focused on the high costs and low ethics of campaign finance, but they have generally overlooked the cost of actually administering elections, which includes facilities, transport, printing, staffing, and technology.
205. (GWD-9-Q17) Unlike most other mergers in the utility industry, which have been driven by the need to save money and extend companies’ service areas, the merger of the nation’s leading gas company and leading electric company is intended to create a huge network for marketing the utilities in question as states open their utility markets to competition.
216. (GWD-13-1) Although she had been known as an effective legislator first in the Texas Senate and later in the United States House of Representatives, Barbara Jordan did not become a nationally recognized figure until 1974, when she participated in the hearings on the impeachment of President Richard Nixon, which were televised nationwide.
4. 通过时态区别which的所指：
488. Like the government that came before it, which set new records for growth, the new government has made laissez-faire capitalism its cornerstone.
Stoneren关于which指代的一个观点：
OG10-114: From the bark of the paper birch tree the Menomini crafted a canoe about twenty feet long and two feet wide, with small ribs and rails of cedar, which could carry four persons or eight hundred pounds of baggage yet was so light that a person could easily portage it around impeding rapids.
当which的潜在指代对象是一个独立的主语结构或独立的宾语结构时，且其指代对象的修饰成分比较简单，那么定语侧重于指代核心名词（在没有语法和逻辑问题的前提下）。
相似题链接：
对于from…to…倒用的合理性：
127. (31278-!-item-!-188;#058&004418)
After decreasing steadily in the mid-1990's, the percentage of students in the United States finishing high school or having earned equivalency diplomas increased in the last three years of the decade, up to 86.5 percent in 2000 from 85.9 percent in 1999 and 84.8 percent in 1998.
(A) finishing high school or having earned equivalency diplomas increased in the last three years of
the decade, up to 86.5 percent in 2000 from 85.9 percent in 1999 and
(B) finishing high school or earning equivalency diplomas, increasing in the last three years of the
decade, rising to 86.5 percent in 2000 from 85.9 percent in 1999 and from
(C) having finished high school or earning an equivalency diploma increased in the last three years
of the decade, and rose to 86.5 percent in 2000 from 85.9 percent in 1999 and from
(D) who either finished high school or they earned an equivalency diploma, increasing in the last
three years of the decade, rose to 86.5 percent in 2000 from 85.9 percent in 1999 and
(E) who finished high school or earned equivalency diplomas increased in the last three years of the
decade, to 86.5 percent in 2000 from 85.9 percent in 1999 and
答案是E
