[讨论]Prep 19

19. 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.

A. while at the same time they have introduced some 100,000 dangerous chemical pollutants, having

B. while at the same time introducing some 100,000 dangerous chemical pollutants that have

C. while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have

D. but introducing some 100,000 dangerous chemical pollutants at the same time that have

E. but at the same time introducing some 100,000 dangerous chemical pollutants, having

答案是B。Prep笔记中说，AC的they指代有歧义：应该是指：未划线部分they可能指methods和pollutants。那么为什么选了B的话，they的指代就没有歧义了呢？难道是因为while从句中没有主语they，就只能指代pollutants拉 ？

个人认为，不是因为WHILE中没有主语they,而是因为they在while中省略了。为什么？当其中的主语和其while引导的从句的主语一致时，while中的主语则可省略。

如有不对的地方请楼下的前辈纠正。谢谢

AC的歧义不是因为未划线部分的they指代不清（they指代pollutants没问题），而是因为句子中的两个they指代不一致吧！（划线的they指代句子主语industrialization and methods）

请问三楼，两个they指代的不是同一个内容会引起什么语法错误吗？

在GMAT的改错中，是不允许的。

再确认一下：一道改错中，同一个代词只能指代一个东东，否则就是错。是这个意思吗？能再举个例子吗？多谢。

15. Recently documented examples of
neurogenesis（神经形成）, the production of new brain cells,
include the brain growing in mice when placed in a stimulating environment
or neurons increasing in canaries that learn new songs.

A. the brain growing in mice when placed in a stimulating
environment or neurons increasing in canaries that

B. mice whose brains grow when they are placed in a
stimulating environment or canaries whose neurons increase when they

C. mice's brains that grow when they are placed in a
stimulating environment or canaries' neurons that increase when they

D. the brain growth in mice when placed in a stimulating
environment or the increase in canaries' neurons when they

E. brain growth in mice that are placed in a stimulating
environment or an increase in neurons in canaries that

B：they指代不明，可以指代brains或mice；第二个they和第一个they不是一个对象

C: they指代brains不对；第二个they和第一个they不是一个对象

不太认同7楼的这个例子：

B错在两个they指代分别都有歧义

C错在两个they的指代造成逻辑意思上的错误

窃以为此例无法证明“一句话里，同一个代词指代不同内容就是错”。

自己找了两个例子，共大家讨论：

OG10-12:

12. Formulas for cash flow and the ratio of debt to equity do not apply to new small businesses in the same way as they do to established big businesses, because they are growing and are seldom in equilibrium.

(A)  Formulas for cash flow and the ratio of debt to equity do not apply to new small businesses in the same way as they do to established big businesses, because they are growing and are seldom in equilibrium.

(B)   Because they are growing and are seldom in equilibrium, formulas for cash flow and the ratio of debt to equity do not apply to new small businesses in the same way as they do to established big businesses.

(C)  Because they are growing and are seldom in equilibrium, new small businesses are not subject to the same applicability of formulas for cash flow and the ratio of debt to equity as established big businesses.

(D)  Because new small businesses are growing and are seldom in equilibrium, formulas for cash flow and the ratio of debt to equity do not apply to them in the same way as to established big businesses.

(E)   New small businesses are not subject to the
                applicability of formulas for cash flow and the ratio of debt to equity in the same way as established big businesses, because they are growing and are seldom in equilibrium.

选项A的错误就是they指代不同意思

Prep-23

23. Unlike most severance packages, which require workers to stay until the last day scheduled to collect, workers at the automobile company are eligible for its severance package even if they find a new job before they are terminated.

A. the last day scheduled to collect, workers at the automobile company are eligible for its severance package

B. the last day they are scheduled to collect, workers are eligible for the automobile company's severance package

C. their last scheduled day to collect, the automobile company offers its severance package to workers

D. their last scheduled day in order to collect, the automobile company's severance package is available to workers

E. the last day that they are scheduled to collect, the automobile company's severance package is available to workers

选项E的错误也是。

再问一下，上面前辈的解释是在确定用WHILE以后的，那当看见这个题目的时候，怎么确定是用BUT 还是 WHILE ?