求教prep55 & GWD21-39代词问题

55. 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 pollutant, having

A: 两个they不一致

B: correct

C: 两个they不一致

D: but不能起到引导状语从句省略的作用，应该改成introduced

E: 同上

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（1）     GWD-21-Q39

Almost like clones in their similarity to one another, the cheetah species’ homogeneity makes them especially vulnerable to disease.

A.      the cheetah species’ homogeneity makes them especially vulnerable to disease

B.     the cheetah species is especially vulnerable to disease because of its homogeneity

C.     the homogeneity of the cheetah species makes it especially vulnerable to disease

D.     homogeneity makes members of the cheetah species especially vulnerable to disease

E.     members of the cheetah species are especially vulnerable to disease because of their homogeneity

E the best ，注意B中的单数无法和like中的复数进行比较。

问题是两个题目中都出现了两个their　和they

如果ＧＷＤ２１－３９选择Ｅ的话．那起不是前后两个their不是一个意思．这样不就和ＰＲＥＰ　５５相违背了么？

马上要考了　请教大牛！！！！

Almost like clones in their similarity to one another, the cheetah species’ homogeneity makes them especially vulnerable to disease.

A.      the cheetah species’ homogeneity makes them especially vulnerable to disease

B.     the cheetah species is especially vulnerable to disease because of its homogeneity

C.     the homogeneity of the cheetah species makes it especially vulnerable to disease

D.     homogeneity makes members of the cheetah species especially vulnerable to disease

E.     members of the cheetah species are especially vulnerable to disease because of their homogeneity

E the best ，注意B中的单数无法和like中的复数进行比较。

问题是两个题目中都出现了两个their　和they

如果ＧＷＤ２１－３９选择Ｅ的话．那起不是前后两个their不是一个意思．这样不就和ＰＲＥＰ　５５相违背了么？

马上要考了　请教大牛！！！！