12. The children were told to keep of the grass.

答案： of改为off．off意为“离开”。

11. As a rule , the workers are paid for the hour.

答案： for改为by．by the hour按小时。

10. what does he usually have at breakfast?

答案： at改为for．have．．．for breakfast"以……作早餐”。

9. My father will be back after three hours.

答案： after改为in.“in+一段时间”与将来时态连用。

8. I was very surprised by seeing her here.

答案： by改为at.be surprised at对……感到吃惊。

7. When are they leaving to London?

答案： to改为for．1eavefor．．．，“动身去……”。

6. She had to do such things at her will.

答案： at改为against．againstone'swill违背某人的意愿。

5. The old man is sitting next his son.

答案： next后加to．next　to在……旁边，靠近。

4. An hour consists by sixty, minutes.

答案： by改为sist of由……组成。

3. Your watch is similar with mine.

答案： with改为to．besimilar　to与……相似。