语法练习

D.whether

2.___ has been known for about a hundred years, its commercial development has taken place since the beginning of the century.

D.As

3.The drill has been designed so ___ through the earth to a depth of 35,000 feet.

D.boring

4.Sharon was supposed to be here at 10 o'clock. She ___ about our meeting.

D.must have forgotten

5.This may have preserved the elephant from being wiped out as well as other animals ___ in Africa.

D.are hunted

答案详解

1.[B]【解析】that从句作名词doubt的同位语。doubt同时在there be结构中作主语。

2.[D]【解析】as引导非限制性定语从句，表达整个主句的意思，as在从句中作主语。

3.[B]【解析】so that...引导目的状语从句，相当于so as to bore或in order to bore。

4.[D]【解析】must have done表示从现在的角度对过去情况进行肯定的推测。

5.[A]【解析】other animals是被猎杀的对象，因此选择被动语态。另外，as well as连接两个对等成分，此处完整结构应为：“the elephant from being wiped out as well as other animals from being hunted in Africa.”from being与前文重复，可以省略。