2 . 这表明对环境的破坏已经成为对人类生存的巨大威胁。(imply，表语从句)
______________ the destruction of the environment has become a great threat to man’s existence.

3 . 从这幅图中我们可以得到的总体信息是，有一个常规的沙漏时间表是很重要的。(表语从句，it)
The overall message we can take from this picture is ____________ to have a routine sand timetable.

5 . 清楚的是，它的优点是显而易见的。
What is clear ________ its advantages are apparent to all.

6 . 选词填空
1. ________ (Where, Who) we shall have the meeting is not known yet.
2. I don’t know ________ (how, that) I can finish my work so soon.
3. ________ (That, Whether) men have learned much from the behavior of animals is rarely new.
4. The fact ________ (why, that) most people believe nuclear war would be madness does not mean that it will not occur.
5. ________ (When, What) will happen is impossible to predict.
6. The teacher asked me ________ (whether, how) or not I finished my work.
7. It is estimated ________ (that, whether) a round trip flight to Mars would take more than a year and a half.
8. We all agree with your suggestion, but the question is ________ (why, who) is to put up the money for the activity.