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。
181. 重点题
The number of people flying first class on domestic flights rose sharply in 1990, doubling the increase of the previous year.
A. doubling the increase of
B. doubling that of the increase in
C. double as much as the increase of
D. twice as many as the increase in
E. twice as many as the increase of
题目释义： The number… rose sharply…, doubling the increase of…
考点：
1. 伴随状语：doing引导伴随状语或者目的状语
2. 前后句关系平行一致
3. 不可数名词，抽象名词不可用many形容
4. AlienX: "of XXX(年份)"在OG/Prep上常出现, 所以of previous year没问题
prep1#245: In no other historical sighting did Halley's comet cause such a worldwide sensation as in its return of 1910-1911.
5. 注意这个题的含义：
不是说：今年的人数(total number)在增长以后，是去年增长人数（increase of the previous year)的两倍。
而是说：今年的增长(increase)是去年(increase)的两倍。
aeoluseros: 这里的double是"make twice as great"(造成两倍的**)的意思，也就是使increase/growth两倍，直译过来就是“今年的人数造成了去年增长人数两倍的增长”. (Explanation from LDOCE: “To become twice as big or twice as much or to make something twice as big or twice as much”)
AlienX: 我觉得doubling the increase of the previous year=使1990年的increase在the increase of the previous year的基础上倍增.
来看另外一个非常像的句子:
P1#242: Retail sales rose 8/10 of 1 percent in August, intensifying expectations that personal spending in the July-September quarter would more than double the 1.4 percent growth rate in personal spending for the previous quarter. (7-9月的个人支出造成了前一季度1.4增长量两倍的增长。)
同理, personal spending in the July-September quarter would more than double the 1.4 percent growth rate in personal spending for the previous quarter=personal spending in the July-September quarter的growth rate在the 1.4 percent growth rate in personal spending for the previous quarter的基础上倍增.
6. Double和twice都可以直接作为predeterminer(如C,D,E选项)，而doubling中的double是作为及物动词(如A,B选项).
选项分析：
A. Correct；这里的double是"make twice as great"的意思，也就是使increase/growth两倍；present participle结构修饰前面整个分句。
B. That无指代对象，有人说that是指代the number，如果是指代the number的话，是累赘的，所以that并不指向任何成分；the increase in previous year是指previous year的增长(这个逻辑doesn’t make sense)，而不是在previous year增长，应该用the increase of the previous year。
C. double应该改为doubling，这样划线成分才能修饰前面整个分句，double as much as是同位语修饰词(appositive modifier)，要紧接其修饰的内容，在此句子中逗号前不是一个figure，所以不能用double as many as这个结构；即便as much as能成功修饰number也不对，数量应该用great来修饰，见下面补充5。
D. Many用法错误，因为the increase不是一个countable quantity(这里the increase可以看做是一个代词，而它所指代的对象就是前面出现过的内容：the number of the people，而the number of the people是一个表达数量的数字而不是可数名词，所以the increase也不能够用many来修饰)；twice as many as是同位语修饰词(appositive modifier)，要紧接其修饰的内容，在此句子中逗号前不是一个figure，所以不能用twice as many as这个结构，awkward。(见下面知识点补充1)；the increase in previous year错误。
E. Many用法错误，因为the increase不是一个countable quantity(from Manhattan)；twice as many as结构使用错误同上。
知识点补充说明：
1. "twice Y" / "X times Y" can definitely be used as an appositive。
2. 注意doubling the increase of 和 double as much as the increase of是两个完全不同的结构。
3. 关于twice as many/much as结构：
(http://www.manhattangmat.com/forums/the-number-of-people-flying-first-t5600.html)
(1) If you say "twice as many", then this construction should be paired with acountable noun.
e.g., twice as many dogs --> "dogs" is a countable noun
(2) If you said "twice as much", then this construction should be paired with anuncountable noun.
e.g., twice as much water --> "water" is an uncountable noun
(3) If the noun in question is already an explicitly numerical quantity, then you should use neither "much" nor "many". Instead, you should just use "twice" or "double" by itself.
e.g., twice the increase --> "increase" is an explicitly numerical quantity
(4) These rules are followed pretty closely.
so, for instance:
twice as much water --> correct, since "water" is an uncountable noun (but is not an explicitly numerical quantity)
twice the water... --> incorrect, since water is not a numerical quantity
twice as much as the increase... --> incorrect; redundant
twice the increase... --> correct
4. 注意不能看到the increase就认定它是不可数的，要用much来修饰，而应该看the increase所指向的东西。
5. 关于numbers与greater和more搭配的另一道题：
OG251. The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than when the use of DDT was sharply restricted in the early 1970's. .
a) extinction; its numbers are now five times greater than
b) extinction; its numbers are now five times more than
c) extinction, their numbers now fivefold what they were
d) extinction, now with fivefold the numbers they had （A）
e)extinction, now with numbers five times greater than
A, the best choice, uses a singular pronoun, its, to refer to the singular antecedent The gyrfalcon, and it properly uses the construction its numbers are now ... greater than. In B, the construction its numbers are ... more is not idiomatic: there are more birds, but not more numbers. Choices C and D use a plural pronoun, their or they, to refer to a grammatically singular antecedent, The gyrfalcon.
Choices D and E wrongly use a phrase introduced by now with to modify The gyrfalcon. In both choices, the phrase confusingly seems to parallel with extinction; a new clause with a present tense verb is needed to state what the gyrfalcon's numbers are now.
6. 关于类似twice as many/much as的结构：appositive modifier（同位语修饰词）。
不仅仅名词，有些形容词也是可以做为appositive modifier的，这种形容词用逗号隔开放在句尾，还是习惯于修饰最近的词语（但是不绝对）。这样的形容词有different from, (double/twice) as many as等。
一道来自Manhattan的模考题：
Antigenic shift refers to the combination of two different strains of influenza; in contrast, antigenic drift refers to the natural mutation of a single strain of influenza.
A. influenza; in contrast, antigenic drift refers to the natural mutation of a single strain of influenza
B. influenza, different than the natural mutation of a single strain, known as antigenic drift
C. influenza, in contrast to the natural mutation of a single strain, known as antigenic drift
D. influenza, different than antigenic drift, which refers to the natural mutation of a single strain of influenza
E. influenza; in contrast to antigenic drift, which refers to the natural mutation of a single strain of influenza
Key: A. 此题里面D选项different than先改为different from。而即便改为different from，也修饰不到Antigenic shift，因为太远了，需要在different from前面加上and is(其他错误暂不考虑)。
不过如果前面的成分比较短，不会引起歧义，这个同位语还是可以跳跃修饰的，比如这个例子：
According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey.
(A) doubling those reported in the 1977 survey
(B) to double the number the 1977 survey reported
(C) twice those the 1977 survey reported
(D) twice as much as those reported in the 1977 survey
(E) twice the number reported in the 1977 survey
OA：E。其中twice跳跃used cocaine修饰20 percent of young adults.
7. as many可以当一个数目来用。但是如果连接twice这样的倍数，则后面要用as many as，做比较来用。
182.
The organic food industry has organized a successful grassroots campaign—using Web sites, public meetings, and also mass mailings—that have convinced the Department of Agriculture to change the proposed federal regulations for organically grown food.
A. using Web sites, public meetings, and also mass mailings—that have convinced
B. using Web sites, public meetings, and mass mailings—that has convinced
C. by using Web sites, public meetings, and mass mailings—in convincing
D. by the use of Web sites, public meetings, as well as mass mailings—that convinced(B)
E. which used Web sites, public meetings, and mass mailings—in convincing
题目释义：The industry has organized a …campaign—using …—that has convinced … to
考点：
1. 破折号在GMAT里的用法：用于插入语，解释说明（代替冒号或分号），话语/语义的中断和转折，反讽。
2. As well as不等同于and，不表示并列关系，而是侧重其前面的部分，后面部分处于从属地位。
3. that引导限定性定语从句，in convincing(in doing sth.)是状语。
4. campaign的固定搭配：正确形式为campaign for/against。
选项分析：
A. and also在列举的时候多余，不过在also有时候是作为强调而且不用在列举中不一定多余（and also还有一种情况下是redundant的：both X and also Y）；have应该改为has
B. Correct；原句含义为：组织了一个成功的草根运动--其中用到了网站、公共集会、广发邮件--该草根运动……
C. By using逻辑含义上不等于using，其表达的是因为通过那三个方式草根运动才是成功的，这个含义不对；in convincing不做定语而是状语，修饰的是前面分句及前面整个分句的动作organized，表达organize是convincing中的一个动作，改变原句合理逻辑含义。
D. By using错误同C；and不可以换为as well as，as well as只是一个修饰语，其使mass mailings与前两项的并列关系改变为从属结构，而且并没有A, B, as well as C的结构；the use of表达wordy；用了convinced一般过去时表示convinced发生在has organized之前，逻辑含义不合理。
E. Which used时态错误，其使得web sites, public meetings, and mass mailings的使用是发生在运动之前，逻辑含义矛盾；in convincing不做定语而是目的状语，改变原句合理逻辑含义。
183.
Despite recent increases in sales and cash flow that have propelled automobile companies' common stocks to new highs, several industry analysts expect automakers, in order to conserve cash, to set dividends more conservatively than they were
A. to set dividends more conservatively than they were
B. to set dividends more conservatively than they have been
C. to be more conservative than they have been in setting dividends
D. that they will be more conservative than they were in setting dividends
E. that they will be more conservative than they have been to set dividends
题目释义：Despite …, analysts expect automakers to be more … than they have been in …
考点：
1. Expect的固定搭配：
意为“预料”时：
sth. be expected to do/be;指望，期望
it is expected that 预期 （与上着一个意思，但是没有上者简洁）(prep 1-107)
expect to do sth.
expect sb./sth. to do sth.
expect that
expect sth.
意为“想要“时：
expect sth. from sb.
expect sb. to do sth.
错误用法：
sth. be expected for sth. to do(也就是说for sth.不能加)
sth. be expected that 错 (T-4-Q31)
it is expected for stb. to do累赘，不如直接用sth. be expected to do/be
expect sb. that 错
2. 比较结构的比较对象要平行：no alternations，no tense changes，no nothing(unretriviable omission)。
3. In doing sth. 和 for doing sth. 都有“在做…这方面”的含义；
而to do sth.通常情况下表示目的，可以翻译为：“为了做…”
选项分析：
A. 实义动词to set(表达预测，将来时)与系动词were不平行，应该是: to set Div. more conservatively than they have done.
B. to set与have been不平行，要在been后面加上setting或改为have set以修正平行。
C. Correct；be + adj + in doing something很顺口, e.g. She is very active in posting questions on CD.；时态也很好：to be表示从现在开始的未来，have been 从过去到现在，时间轴上没有空缺
D. Expect sb. that搭配错误，只能用expect that或expect sb. to do；were的时态问题
E. 不能用Expect sb. that，同D； to set错误，应该改为in setting
184.
Japan's abundant rainfall and the typically mild temperatures throughout most of the country have produced a lush vegetation cover and, despite the mountainous terrain and generally poor soils, it has made possible the raising of a variety of crops.
A. it has made possible the raising of
B. has made it possible for them to raise
C. have made it possible to raise
D. have made it possible for raising
E. thus making it possible for them to raise
题目释义：Japan's rainfall and the … temperatures… have produced … and, …, have made it …
考点：
1. 主语单复数
2. 主谓一致
3. And前后并列，在文中为have produced… and have made it …
4. Make短语：
Make it adj. (to do)
Make sth. Adj.
Make (doing) sth. Adj.
Make N1 N2
选项分析：
A. and前后不平行(run-on)，it无指代对象。
B. 主语(rainfall and temperatures)为复数，和has主谓不一致；them没有指代对象，for them多余
C. Correct
D. for doing是介宾短语，不能用it指代，而to do是不定式可以做名词性成份并用it指代，所以make it adj. for doing错误，应该是Make it adj. to do
E. thus是强调因果关系，并不多余；making和have produced不并列；them没有指代对象，for them多余
185.
Because the budget package in Congress promises a combination of higher taxes and reduced spending that may slow economic growth, many in the credit markets wonder whether the Federal Reserve will compensate and help the economy by keeping interest rates low, or perhaps even if they push them lower.
A. by keeping interest rates low, or perhaps even if they push
B. by its keeping interest rates low, or perhaps even by their pushing
C. by keeping interest rates low, or perhaps even by pushing
D. through their keeping interest rates low, or perhaps even push
E. through their keeping interest rates low, or perhaps it will even push
题目释义： many … wonder whether the FR will compensate & help … by keeping, or even by pushing…
考点：
1. Or并列结构前后要平行对称
2. 动词优于one’s doing
3. 代词指代
4. through和by的区别：表示“通过做B达成了A（A已经做到）”时倾向于through，表示“通过做B做A(A还在被做)”时倾向用by。
选项分析：
A. Or前后不对称；they无所指，Federal Reserve为单数
B. Its keeping不如keeping简洁有效；their指代错误
C. Correct，or perhaps even前的逗号是强调作用
D. Their指代错误；one’s doing不如doing简洁有效；Or前后不对称；compensate and help两个动作都未完成，故用through不如用by好
E. Their指代错误；one’s doing不如doing简洁有效；Or前后不对称；through不如by好
186.
Laos has a land area about the same as Great Britain but only 4 million in population, where many are members of hill tribes ensconced in the virtually inaccessible mountain valleys of the north.
A. about the same as Great Britain but only 4 million in population, where many
B. of about the same size as Great Britain is, but in Laos there is a population of only 4 million, and many
C. that is about the same size as Great Britain's land area, but in Laos with a population of only 4 million people, many of them
D. comparable to the size of Great Britain, but only 4 million in population, and many
E. comparable to that of Great Britain but a population of only 4 million people, many of whom
题目释义：Laos has a land area… but a population…
考点：
1. 比较对象要形式对称，性质相同；特别指出文中size和area是可以比的。
2. land area：土地面积。
3. 连词的运用：仅凭逗号是不可以连接两个句子的。
4. 定语从句的关系连词：that/介词+which。
选项分析：
A. Land area不可以和Great Britain不可比；where引导的定语从句修饰population错误。
B. is和has不平行；land area和size重复；many无指代对象。
C. 定语从句wordy，用形容词短语就可以，更加简洁，而且意思没减少；land area的重复使用也累赘；but后面不成句子，无法与前面平行； with a population of only 4 million限定性修饰Laos错误，显得有很多个Laos。
D. Comparable to the size of Great Britain没有错误；only 4 million in population表达不地道；many无所指；在正式语体里面不应该用and many，而应该用“, many of whom”，否则割裂了many与前句的关系。
E. correct；有说法E中people和population是重复表达，但population和people一个是"数量值"(the number of people),一个人人群，重心不同，并不重复。注意popluation也有all of the people和a city, town的意思，单数名词。
187.
United States Senator Daniel Inouye was appointed to several posts within the Democratic Party during his first term, that included assistant majority whip and vice-chair of the Democratic Senatorial Committee.
A. that included
B. which includes
C. including
D. some of which were
E. among them being
题目释义：DI was appointed to several posts……,including……
考点：
1. 定语从句；普通的非限定性定语从句要用which引导(个别非限定性定语从句依然用that引导，但不在GMAT考核范围之内)，而限定性定语从句要用that引导。(关于限定性定语从句与非限定性定语从句区别见07prep语法笔记)
2. 这里including并不是做伴随使用，Include和continue都很少有V-ing用法，这里的including是介词。
选项分析：
A．引导普通的非限定定语从句用which；改为which后，which与所指的posts相隔太远，也不太好。
B．根据句意，定语从句应该修饰several posts，故为复数，使用includes错误,并且时态上讲应该使用一般过去时；which与所指的posts相隔太远，不好。
C．Correct；including比which included更为简洁、明确，including介词短语修饰前面短语的核心词posts。
D． some of which与所指的posts相隔太远。
E． Being累赘；among them being修饰对象不明确(awkward)，并且无法引导独立主格。
188.
Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.
A. Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are
B. Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
C. Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
D. Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
E. Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,
题目释义：Ns, having done….., are doing sth.……
考点：
1. 句子完整结构，
2. V-ing(present participle)修饰（详见补充说明）。
3. aeoluseros对于Having done知识点的补充说明：
1) 不能作为名词结构，因此不能用该结构作主语。
2) 我对定语、状语的理解是这样的：有的时候同一个成分、结构可以做定语，也可以做状语，只要区分被修饰对象与结合时态等分析逻辑上能不能合理修饰就够了，没必要太在意是做定语还是做状语。也就是说，区不区分定语、状语都可以，关键是要明白定语和状语的功能都是“修饰”(有点像废话，不过我的意思是平时我统一把他们记为“修饰语”，只有在做题目解释的时候才区分一下)。
prep1-188中，A选项"having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood"，你可以把这个成分理解成状语，也可以理解为定语，修饰的都是Neuroscientists这个主体或这个主体发出的动作，只要你把having看做定语和状语时，句意理解起来是一样的，那么就没有歧义问题。
而prep1-97：Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.这里面having可能修饰pollutants，也可能修饰they have introduced some 100,000 dangerous chemical pollutants整个分句，所以having产生了修饰歧义
3) having done可以做非限定性修饰，不能做限定性修饰。
夸克的语法大全里面明确写出having done做限定性修饰是错误的：
The perfective aspect cannot usually be expressed in the finite clause:
wrong: The man having won the race is my brother.
correct: The man who has won the race is my brother.
也就是说.完成时的ing分词形式(having done)作为限制性的修饰是不可以的，但是可以作为非限制性的修饰。
4) having done短语中所表达的内容发生在主句动作之前
5) When having done 结构一定错错，因为不应该有 when。单是 Having done 就够了。Have 有很多地方与正牌动词不同，When 后就不能用 having 了。原因是 having done 是过去，而 when 是当时，所以有冲突。（同理的after/before A do sth. when B do sth.或者after/before when，这样的结构都是不好的。）
4. a wealth of 大量的
选项分析：
A. Correct；
B. 句子结构不完整，and前半分句没有谓语动词；over the past twenty years错误修饰adulthood
C. having amassed改成了amassing时态上发生变化，即amass发生的时间有变化，使得逻辑不合理；句子结构不完整，and前半分句没有谓语动词；over the past twenty years错误修饰adulthood
D. drawing并不是have amassed的直接结果，所以不能以现在分词短语伴随修饰（详解见补充说明3）。
E. 同D
OG12-21对本题解释：
Grammatical construction; Logical predication
This sentence introduces the subject (Neuroscientists), pauses to explain what neuroscientists have accomplished in the past twenty years, and then concludes by explaining what neuroscientists are presently doing as a result of their past accomplishments. The second part of the sentence—the explanation—interrupts the flow of the sentence from the subject (Neuroscientists) to the predicate (are now drawing solid conclusions …); it should therefore be bracketed by commas. The sentence construction should provide a main verb for the subject neuroscientists.
A. Correct. Th e explanatory phrase between the subject and predicate is set off by commas, and the main clause contains both a subject (Neuroscientists) and a corresponding verb (are now drawing).
B. And are indicates that are follows a previous verb, but in fact the sentence has not yet provided a first main verb for the subject Neuroscientists; the sentence is therefore incomplete; over the … years appears to be modifying adulthood.
C. Amassing, like having amassed, functions as an adjective, not a verb; the sentence therefore lacks the first main verb implied by the compound verb construction and are now drawing. …
D. The final descriptor in present tense, now drawing conclusions … does not fit the opening clause, which is in present-perfect tense (have amassed a wealth …) and seems to modify adulthood.
E. Like D, this sentence attempts to attach a present-tense descriptor to a present-perfect clause.
补充说明：
V-ing(present participle)修饰
V-ing结构在句子中可以做定语，状语。
1) 放在句子末尾时（逗号隔开），如果前面是主谓宾结构，如果同时时态上与主句搭配合理，V-ing结构作状语，作为：
① 伴随动作，表与主句动词同时发生的动作
② 伴随结果，表主句动作带来的结果。
此时注意其逻辑主语的判断：其所修饰分句的动作发出者。
2) 如果前面是主系表结构（逗号隔开），由于系动词是一个状态不存在“被伴随”，但是V-ing结构依然修饰的是整个主系表结构，所以后面的V-ing结构也可以被解读为修饰前面的名词成分—主语（如果宾语是名词，也一同修饰，因为主系表结构中主语和宾语所指是同一事物--见OG10-39, OG11-24中对正确选项C的解释）。
例：OG10-39 For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military equipment, a method to protect warriors against enemy arrows and spears.
A. a method to protect
B. as a method protecting
C. protecting
D. as a protection of
E. to protect
OG10-39的解释（注意C选项的解释）：
Choice C is best because the participle protecting begins a phrase that explains what the shields did. Choices A and B awkwardly use the singular word method to refer to items of military equipment rather than to the use of such items. Also, a method of protecting would be more idiomatic than a method to protect in A or a method protecting in B. In B and D, as is incorrect; also, a protection in D has no noun for which it can logically substitute. Choice E is incomplete; used to protect would have been acceptable.
OG11-24的解释（注意C和E选项的解释）
Logical predication + rhetorical construction
The underlined part of the sentence begins a phrase describing items of military equipment. It is awkward and inaccurate to describe items as a method. Replacing the underlined phrase with the participle protecting creates a modifying phrase that clearly explains the purpose of the items of military equipment.
A A method to protect is an awkward reference to items
B The singular a method should not refer to the plural items, as a method protecting is not idiomatic
C Correct. In this sentence, protecting properly introduces a modifying phrase revealing the purpose of the items.
D Beginning the phrase with as is incorrect; using the noun form protection creates wordiness
E The infinitive to protect cannot act as an adjective modifying items; the participial form of the verb, protecting, is required
The correct answer is C.
3) 现在分词在句尾用逗号隔开，必须要注意的一点是这个结构从来都没有失去过“做定语”的功能，只是优先做状语而已，即优先修饰到前面主句的主语和谓语。如OG对本题的解释里：
例：OG12-21
Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.
(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,
OG对D项(代入原句：Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, now drawing solid conclusions about how the human brain grows and how babies acquire language.)的解释: The final descriptor in present tense,now drawing conclusions....does not fit the opening clause, which is in present-prefect tense(have amassed a wealth)and seems to modify adulthood. OG在这个解释里说明了drawing是可能修饰到adulthood的。
***Notice：
但是务必注意，OG对D选项的解释并不是说“现在分词做状语不可以伴随修饰完成时态”，而是指drawing不是have amassed的直接结果，所以无法drawing无法做have amassed的伴随结果（现在分词做伴随起到伴随动作和伴随结果两种功能，前者表示与主句动作同时发生，后者需要是主句动作的直接结果。当被修饰主句已经是完成时态，那么后面的现在分词本身就不可能再与主句动作发生在同一时刻，所以无法以 “伴随动作”的身份出现，只可能行使“伴随结果”的功能）。再如下题就很好地说明了现在分词可以伴随修饰完成时态，行使伴随结果的功能：
OG12-94 The recent surge in the number of airplane flights has clogged the nation’s air-traffic control system, to lead to 55 percent more delays at airports, and prompts fears among some officials that safety is being compromised.
(A) to lead to 55 percent more delays at airports, and prompts
(B) leading to 55 percent more delay at airports and prompting
(C) to lead to a 55 percent increase in delay at airports and prompt
(D) to lead to an increase of 55 percent in delays at airports, and prompted
(E) leading to a 55 percent increase in delays at airports and prompting
解析：Parallelism; Diction
The intent of the sentence is to show two effects of the surge in flights. These effects should be stated in parallel ways, instead of the construction to lead … and prompts … used in the original sentence. Using participial phrases introduced by leading and prompting solves this problem. The phrase 55 percent more delays is not as clear as the phrase a 55 percent increase in delays.
A. To lead and prompts are not parallel; 55 percent more delays is not clear.
B. 55 percent more delay is unclear.
C. To lead and prompt are not parallel; the meaning of 55 percent increase in delay is not clear.
D. Participial phrase introduced by leading is preferable to the unclear infinitive phrase to lead to; an increase of 55 percent in delays is awkward and wordy.
E. Correct. Leading and prompting are parallel in this sentence; the phrase a 55 percent increase in delays is clear and concise.
189. (OG12-123)
She was less successful after she had emigrated to New York compared to her native Germany, photographer Lotte Jacobi nevertheless earned a small group of discerning admirers, and her photographs were eventually exhibited in prestigious galleries across the United States.
A. She was less successful after she had emigrated to New York compared to
B. Being less successful after she had emigrated to New York as compared to
C. Less successful after she emigrated to New York than she had been in
D. Although she was less successful after emigrating to New York when compared to
E. She had been less successful after emigrating to New York than in
题目释义：Less successful after, photographer LJ earned…., and her photographs were……
考点：
句子结构，比较对象对等
1. Less要与than搭配，不能与(as) compared to搭配。
2. Run-on sentence.
aeoluseros关于run-on sentence知识点的补充说明：
找过很多解释，包括一些语法书(也包括老外的)、百度，始终觉得措辞上不合适，不过在一本手册上终于看到了满意的解释：
run-on sentence 连写句：
连写句指错误地将两个独立分句合写在一个句子里面没有正确地用标点分离。
连写句有两种类型：
溶合句(fused sentence)：根本不使用标点把两个独立分句合写在一个句子里
逗号错误(comma splice):使用逗号但没有并列连词将两个独立分句写在一个句子里。
BTW: 所谓的独立分句即"主句"，其对应的是"从句"，都属于"分句"。
而run-on sentence的重点在于其改正方法：
1） 分为两个句子
2） 用一个逗号加上and, but, or或者其他并列连词
3） 两个句子中间使用分号
This sentence compares the success J experienced after moving to New York to the success she had previously experienced in Germany. The phrase less successful anticipates the conclusion of the comparison with the phrase than… . The main subject of the sentence is photographer LJ , and the main verb is earned . The opening clause She was less successful…. Therefore creates a comma splice if the comma is not followed by a conjunction. The most efficient way to incorporate the information about J’s comparative successes in Germany and in New York is to turn the clause into an adjectival phase describing J. (FROM OG12)
选项分析：
A．Less successful… anticipates than rather than compared to… ; a comma is insufficient to join two independent clauses into a single sentence.
B．As compare to is an incorrect way to complete the comparison introduced by less; being… is unnecessarily wordy and awkward.
C．Correct.
D． When compared to is an incorrect phrase to complete the comparison introduced by less.
E． A comma is insufficient to join two independent clauses into a single sentence; past-perfect tense is misleading, since it refers to J’s experience in New York, which in fact followed her experience in Germany.
190.
The thirteen original British colonies in North America, some formed as commercial ventures, others as religious havens, each had a written charter that set forth its form of government and the rights of the colonists.
A. some formed as commercial ventures, others as religious havens, each had a written charter
B. some being formed as a commercial venture, others as religious havens, all of which had written charters
C. some that formed as commercial ventures, others as religious havens, all had written charters
D. with some being formed as a commercial venture, others as religious havens, all had a written charter
E. with some formed as commercial ventures, while others as religious havens, each had a written charter
题目释义：The thirteen…., some…, others…, each…
考点：
1. 独立主格，表示伴随，所以必须修饰主谓宾结构，而非主系表结构。
独立主格三种形式：
1)一般形式（独立部分与主句部分无太多关联）n.+n.，n.+V-ed/v-ing，n.+介词短语/形容词短语
2)with形式（与主句主语有紧密的逻辑关系）：with+宾语+宾补，如：with+n.+v-ed/v-ing/to do/介词短语/形容词短语(注意可以用with + noun. + to do的形式，用不定式表示了一个将来的动作)
3)each形式（必须前面有复数名词）： each+v-ed/v-ing，each+介词短语/形容词短语，each+n.+介词短语
*：with型独立主格在GMAT中常常被判累赘。
2. 固定搭配some…others
3. set forth 阐明, 宣布, 提出, 陈列, 出发
选项分析：
A. Correct；some formed as commercial ventures, others as religious havens做为the thirteen original British colonies in North America的同位语；略去中间同位语，代词each跟在复数主语the thirteen original British colonies in North America后起强调作用。
B. Being多余；all与后面的its 单复形式不统一；全句缺少谓语动词
C. some that formed结构中some在定语从句中做主语，主动行使form动作错误；all与后面的its 单复形式不统一
D. with的存在使得some并不是指代colonies，而是与colonies相关的东西；all与后面的its单复形式不统一；这里with并没有夹心修饰的歧义，因为all/each和colonies是同一样东西，所以向前向后修饰逻辑上都一样（夹心修饰见prep 1-207补充说明）。
E. with的存在使得some不是指代colonies，而是与colonies相关的东西；while多余，因为后面的others as religious havens中没有谓语动词，while必须省(如果有谓语动词则不能省，如Some cleaned the windows, while others mopped the floor)。
