谢谢大侠指教~讨论prep中的题目~

penguinvino

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
这道题B选项确实是最好的，但是prep解释中说“while 引导从句时,如主从句的主语一致,且从句谓语又含有 be,则从句主语和 be 可省略。while 后可直接跟现在分词、名词、形容词或介词短语。如:We are teachers while (we are) serving as students.我们边当老师边当学生”。这里我想问一下，如果是这种情况的话那么还原后应该是“while at the same time Industrialization and modern methods of insect control are introducing some 100,000 dangerous chemical pollutants that have”这里面“are introducing ”和前面的“have improved ”是不是太不平行了呢？还是说“sb do… while doing”是固定用法？那么什么情况下这么用呢？谢谢大侠指教~

ciciwenwen

补充一点是，刚又做到这道题，RON说：D中的pollutants at the same time that have, 其中的that从句是修饰pollutants的，这里没问题，虽然中间插入了一个短语，不touch也是对的。

ciciwenwen

我的看法：
1、but应该类似and，所以要从句，最少要平行，前半句是have improved是一个有时态的谓语动词，后面有introducing的错误。杀掉D\E。
2、C立马杀掉，which可以引导非限制性从句，但是放在same time后修饰time，错误。
3、having修饰不明，我可以说是前句中的methods....having了，这个明显不对，因为要表达的是chemical pollutants。杀掉A。
所以，B是最好的，虽然我一直模糊记得GMAT说while要加从句，但是看这个就知道，的确可以不加从句。且while at the same time 基本都算一个固定的组合。