[讨论]请教GMATPrep里的一道题！

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

ANSWER: B      MINE: A

做题的时候只在AC间徘徊，因为觉得have improved... while... have introduced是句子的并列谓语。

但后来又觉得A项和B项最后用having 和which have都不能准确的修饰chemical pullutants。还是B的that have最perfect。但是B项中的introducing是什么成分，难道它的执行者不是Industrializations and modern methods吗？

Confused了！

请NN们指教！

my answer is also A,wait for someone else to solve it.

自己顶一下~

我自己觉得像, having这种形式好像是指代全句的，但这句话只是要说明pollutants have所以用从句就成了。

I prefer B.

1)從屬子句之主詞若與主要子句之主詞一致, 則從屬子句之主詞可省略, 謂語改成分詞：

But/while/because ...S+V... 改成

But/while/because ...Ving

2) pollutants必須要用that來修飾

这是ETS常考的一个考点啊

having表示某事物一贯拥有的一种状态

而that have则是做定语表达一时发生的事情

you they的都不对，因为一个句子里有2个they指代不同的话就会出奇异。

but也不对，因为but是连词，它后面接句子E,D的But后面不是句子。