5. 我们已将部分镇中心变成了一个新公园。

4. 这个镇几年中已经发生了很大变化。

3. 政府必须采取措施改善情况。

2. 把垃圾扔进河里是不对的。

四、 完成句子

1. 从那时起，我们就住在这个地区了。

10. What you (do) if I can’t go there with you tomorrow?

9. The policeman told them (not stay) there. It was dangerous.

8. It's necessary for us (realize) the importance of environment protection.

7. They came to see me while I (prepare) for my test yesterday morning.

6. —Who will you invite (go) on a trip with you in the summer holiday?

  —Maybe Lily and Lucy.