- UID
- 434759
- 在线时间
- 小时
- 注册时间
- 2009-4-11
- 最后登录
- 1970-1-1
- 主题
- 帖子
- 性别
- 保密
|
求助大全969,前人讨论没说过的新问题 969. Leaching, the recovery of copper from the drainage water of mines, as a method of the extraction of minerals, it was well established as early as the eighteenth century, but until about 25 years ago miners did not realize that bacteria taken an active part in the process.
(A) as a method of the extraction of minerals, it was well established (B) as a method of the extractionof minerals well established (C) was a well-established method of mineral extraction (D) was a well-established method of extracting mineral that was(C) (E) had been a method of mineral extraction, well established 答案C,我选E。 对于E,大全简注说had been时态错,可是既然是发生在eighteenth century的事,肯定比25 years ago要早,25 years ago时的事情都已经用了过去时did not realize,那18世纪不应该是had been吗? |
|