题目内容：

根据下列句子及所给单词的首字母，写出各单词的正确形式（每空限填一词）。

1.As we all know, Nelson Mandela was once s_______________ to 27 years in prison.

2.On the top of the high mountain, they found the air was hard to b____________.

3.He is not a Chinese but he can speak Chinese f_____________.

4.Most scientists present at the meeting voted a_____________ the plan for it would be harmful to the air.

5.They all b__________ out laughing at the funny joke.

6.She is so generous that she gives the poor food and clothing and asks for nothing in r________.

7.After the earthquake, the whole city lay in r__________.

8.A majority of people like to play o__________ rather than stay indoors when it is fine.

9.People in all countries hope for a p_____________ world instead of one filled with wars.

10.We need more e___________ to prove that he is the thief.