参考答案：

一、 单词拼写

1. billion 2. gentle 3. atmosphere 4. pull 5. satellites 6. Multiplies 7. harmful 8. Climate

二、 原文填空

1. What it was to become

2. so；that

3. made it possible for life to develop

4. twice as far as

5. now that

三、 单选

ACDD BBAD

四、 用time的适当形式填空

(1) in time (2)At one time (3)At times (4)Take your time

五、 完成句子

1. Now that

2. in time

3. Watch out

4. Cheer up

5. came into existence

6. prevent; from being damaged