[求助] Prep 07-97

rainytang

130. (31416-!-item-!-188;#058&004490)【与97相同】

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

正确选项为B，虽然别的选项都有错误，但是B中的While和at the same time不是redundant了么，按理说应该完全有理由排除，即使这里while表转折或者对比，但后面的introducing还是说明了while表当...的时候，有点想不通，请教高手

歪歪的

这道题我也查了很久，可以确定的是while这里表转折~http://www.manhattangmat.com/forums/industrialization-and-modtern-methods-of-insect-control-have-t460.html 这个帖子里面有提到

while+doing的用法我一直不太懂，例如og134
Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, fatigue among shift workers, and have raised  production efficiency in various industries.
(C) and fatigue among shift workers while raising
如果像笔记里写的while后面句子谓语是be的话省略，这里前面是have reduced后面是are raising？

这道prep的题我觉得也不能用省略be来解释啊……
坐等高手