prep 1-97

以下是引用charlie6989在2008-10-8 20:23:00的发言：
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

Ans:B

笔记：Ｄ(D) but introducing不能和have improved构成并列
小弟此处认为有些疑问
参考ＯＧ11#15
The Iroquois were primarily planters, but supplementinq their cultivation of maize, squash, and beans with fishing and hunting.
(A)    but supplementing
(B)    and had supplemented
(C)    and even though they supplemented
(D)    although they supplemented  
(E)    but with supplementing

OG解释
The participle supplementing would normally be expected to modify the first clause, describing or extending its meaning, but the logic of this sentence demands a contrast, not an extension
不管前者连接词是否为转折用词  , 后面有-ing分词就会被认为延伸前句
大家来讨论看看小弟理解是否有误