今天做PREP,语法错得很没方向. 请教!!!

有一题是这样的:

Industrialization and modern methods of insect contol have improved the standard of living around the globe while at the same time they have intoduced 100,000 dangerous chemical pollutants, have gone virtually ungregulated sine they were developed more than 50 years ago.

A.while at the same time they have intoduced 100,000 dangerous chemical pollutants, have gone virtually ungregulated sine they were developed more than 50 years ago.

B.While at the same time intorducing some 100,000 dangerous chemical pollutants that have

C.while they have intoduced 100,000 dangerous chemical pollutants  at the same time, which have

D和E错误明显，很容易排除，我就不抄了。

答案是B.

不明白while是连词,后面跟的不是句子而是分词结构,很不明白!!为什么啊???

while + at the same time  looks redundant and wordy.

就是,那还为啥选B

有NN能解释下吗~~~

就快考了,模得自己很没底~~~

the structure of while ... ing   is nothing wrong.

Among A, B and C,  B is the best.

大致看了一下也是觉得B最好

A中我想按ETS思路,首先they的指代不明确,其次have前的逗号给的莫句其妙,如果前有插入语，也许还能考虑一下，但这里实在是不清晰

Ｅ中which have绝对是指代不明，按就近原则应该修饰time而逻辑上却是在说pollutants典型的指代不清

所以从主要错误着眼根本不用去考虑while和at the same time的问题，要抓ＥＴＳ给出的主要矛盾

顶一下

这题我也选A

主要也视觉得while 要接S+V

while+ ___ing 这型式有NN可以解释一下吗感谢感谢

我是这样理解的，不知对不对

i'm not NN, but i can explain your question.

Participle clauses after conjunctions and preposition:

Participle clauses can be used after many conjunctions and prepositions, such as after, before, since, when, while, whenever, once, until, on, without, instead of, inspite of and as.  

After talking to you I always feel better.

After having annoyed everybody he went home.

Depress clutch before changing gear.

She's been quite different since coming back from America.

When telephoning from abroad, dial X, not Y.

Once deprived of oxygen, the brain dies.

Leave in oven until cooked to a light brown color.

On being introduced, British people often shake hands.

They left without saying goodbye.

She struck me as being a very nervy kind of person.

She met Andy while working on a production of Carmen.

原来如此

非常感谢高手解题