标题: 求NN解答一道prep题目！关于while的用法 [打印本页] 作者: Lizzy233 时间: 2014-9-17 11:06 标题: 求NN解答一道prep题目！关于while的用法 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, and
have
(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have
(E) but at the same time introduce some 100,000 dangerous chemical pollutants, having
这道题选B，能每个选项解释一下吗？
while和at the same time不是语义重复吗？GMAT中while的用法是比较偏向同时发生的意思吗？while doing和前面的不平行啊~为什么作者: 暴躁的大叔 时间: 2014-9-17 16:16
while的用法是偏向 比较 的含义，和 at the same time不存在重复
这里正确选项B while doing是做伴随状语，主语跟主句主语一样，伴随状语不需要平行啊。作者: lemon123 时间: 2014-9-23 15:24
while doing偏向比较主句与从句动作之间的不同（在主语相同情况下）。很明显这里是想比较improve和introduce，无论前面improve是用什么时态
