来源：中国MBA教育网综合报道 作者：shicui 责任编辑：shicui 03/01/2017
在职mba英语语法句型之情态动词本身有语义, 表示说话人的语气或情态, 但语义不完整, 不能单独作谓语动词, 一般只能与动词原形一起构成谓语动词。现就考试中出现频率高的情态动词及其用法作些说明:
与must有关的题型经常与其后面应跟什么时态有关. 在有must的句中, 常表示说话人在进行依据较充分的推测。至于用哪些时态, 则有两个参考标准: 句中的时间状语和句间的关系。
You look so sleepy. You must have sat up late last night.
I mailed that letter a week ago. He must have received it.
must + have + -ed分词: 用于肯定句, 表示对过去情况的推测, 意为“肯定, 一定”。
You had only a little egg at breakfast today. You must be hungry now.
Must 加动词原形的进行式, 表示对现在发生动作和事物的猜测, 有“一定, 准是”的意思。
其他情态动词如may (might), should (ought to), can(could), need的用法分别如下:
may(might) + have + -ed 分词: 用于肯定句和其他否定句, 表示对已发生事情的不肯定的推测, 意为“可能, 大概”, 其中might较may语气更弱, 把握更小。
They may have derived inspiration from these words.
Our manager may (might) have gone to Guangzhuo attending Spring Fair there last week.
除了其一般的用法以外, should 也表示说话人的感情如愤怒, 惊奇, 失望等。
I am sorry that he should be so stubborn.
Why should I go there while she stays home?
should(ought to) + have+ -ed 分词句型: 指过去的事情。如果是肯定句, 表示过去本应发生的事却没有发生, 含“遗憾、责备、建议或指正”等意味; 如果是否定句则表示已发生了本不该发生的事。
You should have told him the paint on that seat is wet.
They should’t have left so soon.
用于否定或疑问句中, 后面跟动词原形的完成式时, 表示对过去发生的事件的“怀疑或不肯定”。could 比can更表示说话人语气的不肯定。
Nobody could have foreseen all this.
It couldn’t have been Mr. Smith. He has gone to China.
needn’t + have + -ed分词: 表示过去做了但不必做的事情, 意为“其实不必”。
You needn’t have walked up; you could have taken the lift.
You needn’t have watered the vegetables, as it is going to rain.
Exercises 11 Choose the best answer to complete the following sentences:
1. The room is such a terrible mess. It ____cleaned as the landlady said.
A. mustn’t be B. mustn’t have been
C. can’t be D. can’t have been
2. With her hands so full, she____to the concert last night.
[FS:PAGE] A.wouldn’t go B. oughtn’t to go
C. shouldn’t have gone D. mustn’t go
3. We ____ her letter last week. We don’t know what has happened to her.
A. must receive B. must have received
C. ought to receive D. ought to have received
4. There ____be an open window somewhere, I can feel cold air coming in.
A. should B. must
C. seem D. ought
5. If the doctor had been available, the patient _______.
A. could not have died B. should not have died
C. wouldn’t have died D. would not die
6. Since it’s snowing so hard, we____at home.
A. had better staying B. should stay
C. had better to stay D. might as well stay
7. The wine bottle is nearly empty; you ____ a lot.
A. may have drunk B. ought to have drunk
C. must have drunk D. could have drunk
8. According to western culture, you ____ask a woman her age; it is impolite.
A. needn’t(不必) B. don’t have to
C. mustn’t (不可以) D. have not got to
9. She didn’t know you were here; otherwise she ____ to meet you.
A. would have come B. had come
C. must have come D. would come
10. I wish you____a little longer.
A. would stay B. will stay
C. would have stayed D. will have stayed