如果你有时间，你可能去购物。

⑷ I requested that he (should) complete the task on time .

我要求他准时完成这个任务。

⑸ I'm surprised that he should say so .

他竟然这样说， 这使我很惊讶。

⑹ He should \ought to have completed the job 他本应该完成这项工作。

用法小结： ⑴

⑵

⑶.

⑷

⑸

⑹

2.ought to \oughtn't to

观察：⑴You ought to go and see your mother in the hospital tomorrow. 明天你应该去医院看看你母亲。(侧重责任、义务)

　　　⑵ You oughtn't to have read the newspaper in class . 你本不应该在课上读报纸。

　　　⑶. You ought to take care of your brother , oughtn't you ?

用法小结： ⑴

⑵

　　　　　　⑶

3.mustn't ; don't have to ; needn't

观察： ⑴ I don't have to go now , because the school broke up . 我不必现在去了，因为学校放假了。

　　　　⑵ You mustn't smoke in public . 你绝地不允许在公共场合吸烟。

　　　　⑶. There is plenty of food . You needn't go shopping .

　　　　⑷ There was plenty of food . You needn't have gone shopping .

用法小结： ⑴

⑵