成考高起点英语语法归纳与练习（十五）

文章作者 100test 发表时间 2007:03:23 16:28:49
来源 100Test.Com百考试题网

lesson 15 　情态动词（二）

内 容 提 要

情态动词有can（能），may（可以），must（必须），have to（不得不），ought to（应该），dare（敢），used to（过去经常），had better（最好），would rather（宁愿）。在肯定句中它们后边都要接 动词原形 .在否定句中，can，may，must和dare后边加not；have to和ought to分别在have和ought后加not；used to的否定式可用used not to，也可用didnt use to，但后者用得较多；had better和would rather的否定式分别是had better not和would rather not.这些情态动词与现在完成时连用在某种意义上有一定的虚拟性。

情态动词与完成时的使用

一、must have ED分词：用于肯定句，表示对过去情况的一种肯定推测，表示“肯定，一定”

1） It around nine oclock when I drove back home because it was already dark.

［A］ had to be ［B］ must have been ［C］ was to be ［D］ must be

2） Johns score on the test is the highest in the class；

［A］ he should study last night

［B］ he should have studied last night

［C］ he must have studied last night

［D］ he must had to study last night

3） After searching ［A］ for evidence in the house，the police concluded ［B］ that the thief must have come in ［C］ through the window and stole ［D］ the silver while the family was asleep.

二、may （might） have ED分词：用于肯定句和否定句，表示对已发生事情的不肯定的推测，相当于“可能，大概，”其中might较may 语气更弱，把握更小

She might have gone to see her doctor last week， but I am not sure.

上星期或许她去看医生了，但我不敢肯定。

Dont worry， your husband may not have been hurt seriously.

别急，你丈夫也许伤得不厉害。

三、should（ought to） have ED分词：肯定句表示过去本应发生的事却没有发生；否定句表示已发生了本不该发生的事。前者可译为“本应，”后者为“本不该”

You should have apologized to her for 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，thats 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 cant 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。

“couldnt have ED分词”还表示无论如何也不可能或没有做到