还没有登录哦！
[Sentence Correction]
试题详情
题目：
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.
选项:
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
答案:
B
提问：
实在不理解while doing这是一个什么结构？什么作用？可以麻烦老师细讲下么？然后对比下选项 谢谢
解答：
点赞0
阅读24018
问个问题
注册太麻烦？点这里查看免费答疑吧！
博币不足
加"GMAT小百科"小智微信
直接送200
