8. Is there any (可能性) that you’ll be back before Sunday?

7. One of the main (缺点) of the job is the bad environment

6. What (百分数) of the Earth is covered by the sea?

5. To her surprise,the (陌生人) did not go away.

4. I followed the (外星人) to see where he was going.

3. There is a (距离) of four miles between my house and the sea.

2. Las Vegas is one of the biggest (娱乐) centres in the US.

1. The helicopter (盘旋;转圈) the airport before landing.

19. 被存放在银行里20. 没有空气污染的交通

17. 火星生活指南18. 受欢迎的娱乐形式