2016年江西成考英语情态动词归纳及练习二(2)

not soon replying to the letter. 你本应向她道歉，说明为什么没能及时回信。（可你没这么做）

　　4）You yesterday             if you were really serious about your work.

　　[A] ought to come[B] ought to be coming[C] ought to have come[D] ought have come

　　四、can（not）+have+ ed分词

　　He is an hour late —— He can have been delayed by fog. Of course，that's a possibility.他迟到了1小时，可能因为大雾而耽搁了。当然这只是可能性问题。

　　The poem can not have been written by her since she was only five years old then.这诗不可能是她写的，因为她那时才5岁。

　　五、“could+have+ ed分词”有时用于表示过去的时间，说明某事可能或不可能已发生；有时可表示过去本来可以做某事，但却未做

　　I simply can't understand how he could have made such a mistake. 我简直不明白他怎么会犯那样的错误。

　　He walked there，but he could have taken a taxi. 他走着去了，可当时完全可以坐出租。

　　“couldn't+have+ ed分词”还表示无论如何也不可能或没有做到

　　I couldn't have called you. I wasn't near a telephone. 反正我也不可能给你打电话，我附近没有电话。

　　5）“We didn't see him                at the lecture yesterday.”He it.

　　[A] mustn't attended[B] couldn't have attended[C] would have not attended[D] needn't have attended

　　六、needn't+ha