PREP SC-97

haoqianruhaos

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
为什么c不行？但是b。。。

cckjenius

c中which没有紧跟先行词，at the same time将which与先行词隔得太远，没有把at the same time提前好。

还有while后面的they指的是主语的industrializatio那一串的主语，而划线后的they应该指的是pollutants，指代的内容不一样，容易让人误会为后面的they也指industrialization

linbingcheng

我觉得they 指代的是一致的，都是主句主语industrialization and  modern methods of insect control .但是问题出在了at the same time的位置发生改变，意思也就变了。

tofreesky

选项里面的they 和划线后面的they指代不一致