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题库 / Prep2007E1-SC-97
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.
while at the same time they have introduced some 100,000 dangerous chemical pollutants, having
while at the same time introducing some 100,000 dangerous chemical pollutants that have
while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have
but introducing some 100,000 dangerous chemical pollutants at the same time that have
but at the same time introducing some 100,000 dangerous chemical pollutants, having
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c的问题应该就是which形容了time
a. 这里面 having 可能修饰 pollutants，也可能修饰 they have introduced some 100,000 dangerous chemical pollutants 整个分句，所以 having 产生了修饰歧义
while doing 看来是可以的
de.copy前面小姐姐的解释
“de 不能用but，因为but必须连接两个句子，当他连接成分的时候一般是省略的现象，这里but doing前面没有和他平行的对象，所以不对”
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