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.
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
A选项里having作定语修饰pollutants, redundant and not clear,而且they的指代有不清,
B选项用while doing的结构承接了前主句表结果,且用了that定语从句修饰pollutants,没什么明显问题。
C选项,While表达的是于此同时的意思,但是却变成了they have introduced并列,感觉并非原意而且while + doing一般表示同时性,而且pollutant与which之前插入了at the same time, 导致修饰不清。
DE都用了but,强调了转折而非同时性,D中的pollutants at the same time that have也是有修饰问题,E也是pollutant, having blabla 这种非限定修饰GMAT不会写入正确里的