[讨论]Prep 19

xyzGZ

GMAT中的SC的解题技巧就是应该竖着读选项，从最明显的地方下手。这道题，第一眼应该观察到句末的差别：Ving，which，that。那么一眼看到C和D的which或that都是修饰time，和划线后面部分的意思不搭配，错。 E中的but是平行结构的暗示词，既然but后面+Ving形式，那么句子前面要有一个Ving形式与之平行。发现句子没有， 所以错。A和B最大的区别在于一个有they，一个没有they。因为句子前面有methods，是复数，所以they是指代methods呢还是指代Industrialization and modern methods呢，有歧义，所以错。因此选B。此外，while可以引导状语从句，其所引导的动词可以是完整的动词（即引导从句）也可以是Ving形式。本句中引导Ving形式，其主语省略，证明和主句主语一致，避免歧义。

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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thanks! I got it