1 . 我们刚到达目的地就下雨了。(when)
We ________________ it began to rain.

2 . 我每次去北京，都会去参观长城。(each time)
________________ I would visit the Great Wall.

4 . He happened to be out ________________ (上次我去拜访他时). (根据汉语提示完成句子)

5 . ________________ (每次我遇到困难时), I turn to him for help. (根据汉语提示完成句子)

6 . 每次我们喝软饮料的时候，里面的糖会形成酸，并侵蚀我们的牙齿大约20分钟。
The sugar in soft drinks forms acid and attacks our teeth for about 20 minutes ________________.

7 . It wasn’t ______ they had a discussion that they made up their mind. (用适当的词填空)

8 . 当我刚开始使用手机做作业的时候， 我有段时间难以阻止自己在它上面玩游戏。

9 . 每次读《老人与海》时，我都会对那位老人有更好的理解。(The Old Man and the Sea)

10 . We have a registered letter for you. You can pick it up ___________ (在你方便的时候).