prep-1-97 求助！（没被讨论过的部分）

judyenglish

97. (29753-!-item-!-188;#058&003991)

 

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

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            问题： D及E选项的错误：笔记上说是因为but introducing不能和have improved构成并列——我不明白为什么but introducing和have improved要构成并列？

judyenglish

怎么没人解答？难道是我的问题太白痴了？！

judyenglish

我顶！

judyenglish

我再顶！！！

aeoluseros

要用have introduced才能与have improved平行...因为是同时发生，表示对比，所以需要but两边平行.用while引导把第二部分降为状语则不存在这个问题