prep07 97题..看了以前的帖，问题还是没有解决掉...求NN帮忙

yqhpsyche

97.(29753-!-item-!-188;#058&003991)
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

我选的D，答案选B，笔记上的解释说

(A)第二个they有指代不清的嫌疑,既可能指代第一个they所指代的Industrialization and modern

methods of insect control又可以指代chemical pollutants；句尾的分词结构having gone…目的是作

pollutants的后置定语，但有作状语的歧义存在。

(B)正确,使用sb do… while doing结构省掉了they避免了同第二个they产生指代不清的嫌疑;

使用限定性定语从句符合逻辑意思

(C)使用which作非限定定语从句,导致逻辑错误,表明所有的chemical pollutants都 have gone
virtually unregulated;第二个they有指代不清的嫌疑

(D) but introducing不能和have improved构成并列

(E) but… introducing不能和have improved构成并列;句尾的分词结构having gone…目的是作

pollutants的后置定语，但有作状语的歧义存在

对D的解释说introducing不能喝haveproved并列，可是B选项也用的是introducing啊，为什么就可以呢？  
    求解答...谢谢

yqhpsyche

自己顶！ 求帮忙.....  希望各位不吝赐教呀

kyle7

B选项并不是一个平行结构，而是由while引导的一个状语从句省略后的结果。
补全后是：while at the same time they are introducing……

stephanie213

我觉得B的ing形式，是一种放句尾表伴随的情况，与此同时发生的事件。
D中就不对了，因为but做连词只能连接句子，只有当but 前后的两个句子的主语和时态一致的情况下，才可省略主语，eg: They are not talking but singing.