6. Only a tiny part of the energy that comes from the Sun,         0. 023% ，is actually used by green plants to produce food.

   A. much   B. approximately

   C. punctually   D. mainly

5. Many AIDS patients think it        to have AIDS,so they usually keep it a secret from others.

   A. doubtful   B. harmful   C. shameful   D. painful

4. The purpose of this first step is to        the nature and importance of the problem,but nobody would listen.

   A. find   B. discover   C. clarify   D. classify

3. They called on Western nations to        more money to the poorest nations in Africa.

   A. earn   B. commit   C. raise   D. save

2. Wheh you get involved in sports,a lot of racial        are broken down because players develop friendship quickly.

   A. approaches   B. threats   C. barriers   D. hardships

1. Nowadays senior high school students are burdened with too many         ，which is making them less and less confident.

   A. motivations   B. expectations

   C. amusements   D. opportunities

10. By the time this letter reaches you,I        the country (leave)

当你收到信时，我将巳经离开这个国家了。

9. With        on the family album,Jack thought of the fun he had when he lived with his grandparents (fix)

眼盯着家庭影集，Jack回想着和祖父母一起生活时的欢乐。

8. The local government decided to close down some of the factories,which           the environment (harm)

地方政府准备关闭一些巳经对环境造成很大伤害的工厂。

7.       ，the train will have left (by)

在你到达车站之前,火车就已经走了。