情态动词的用法总结(2)

　　2) must have+done sth., 表示对过去时间里可能发生的事情的推测,语气较强,具有“肯定”的意思。

　　e.g. --- Linda has gone to work, but her bicycle is still here.

　　--- She must have gone by bus.

　　3) ought to have done sth.\should have done sth.本应该做某事,而事实上并没有做; 否定句表示“不该做某事而做了”。

　　e.g. You ought to (should) have been more careful in this experiment.

　　He ought not to have thrown the old clothes away.(事实上已扔了。)

　　注: ought to 在语气上比should 要强。

　　4) needn’t have done sth. 本没必要做某事

　　e.g. I dressed very warmly for the trip, but I needn’t have done so. The weather was hot.

　　5) would like to have done sth. 本打算做某事

　　e.g. I would like to have read the article, but I was very busy then.

　　7. 情态动词should和ought to

　　should 和ought to 都为“应该”的意思,可用于各种人称。

　　e.g. --- Ought he to go?

　　--- Yes. I think he ought to.

　　表示要求,命令时,语气由 should(应该)、(had better最好)、must(必须) 渐强。

　　8. 情态动词had better表示“最好”

　　had better 相当于一个助动词,它只有一种形式,它后面要跟动词原形。

　　had better (not) do sth.

　　e.g. It is pretty cold. You’d better put on my coat.

　　She’d better not play with the dog.

　　had better have done sth.

　　表示与事实相反的结果,意为“(过去)本来最好”。

　　e.g. You had better have come earlier.

　　9. 情态动词would rather表示“宁愿”

　　would rather (not) do

　　would rather…than…宁愿…而不愿

　　would sooner\ had rather\ had sooner表示"宁愿"、"宁可"的意思。

　　e.g. If I have a choice, I had sooner not continue my studies at this school.

　　10. will和would

　　1) would like to do = want to 想要

　　e.g. Would you like to go with me?

　　2) Will you…? / Would you like…?

　　表示肯定含义的请求劝说时,疑问句中一般用some, 而不是any。

　　e.g. Would you like some cake?

　　3) 否定结构中用will, 一般不用would, won’t you是一种委婉语气。

　　e.g. Won't you sit down?

　　11. need和dare

　　这两词既可做实义动词用,又可做情态动词用。作为情态动词,两者都常用于疑问句,否定句和条件句。并注意回答用need 提问的句子时，肯定回答用must。

　　need 作实义动词时后面的不定式必须带to,而dare作实义动词用时, 后面的to时常可以被省略。

　　1) 实义动词: need+ n. / to do sth.

　　2) 情态动词: need,只用原形need后加do,否定形式为need not.

　　e.g. ---- Need you go yet?

　　---- Yes, I must. / No, I needn't.

　　3) need, want, require, worth(形容词)后面接doing也可以表示被动。

　　need doing = need to be done

　　Exercises

　　1. A left-luggage office is a place where bags ____be left for a short time, especially at a railway station.

　　A. should B. can

　　C. must D. will (B)

　　2. How ___ you say that you really understand the whole story if you have covered only part of the article?

　　A. can B. must

　　C. need D. may (A)

　　3. — The room is so dirty. ___we clean it?

　　— Of course.

　　A. Will B. Shall C. Would D. Do (B)

　　4. My English-Chinese dictionary has disappeared. Who ___ have taken it?

　　A. should B. must

　　C. could D. would (C)

　　5. — Is John coming by train?

　　— He should, but he ____ not. He likes driving his car.

　　A. must B.can

　　C. need D.may (D)

　　6. — I heard they went skiing in the mountains last winter.

　　— It ____ true because there was little snow there.

　　A. may not be B. won’t be

　　C. couldn’t be D. mustn’t be (C)

　　7. It has been announced that candidates __ remain in their seats until all the paper have been collected.

　　A. can B. will C. may D. shall (D)

　　8. — I hear you’ve got a set of valuable Australian coins. ___ I have a look?

　　—Yes, certainly.

　　A. Do B. May C. Shall D. shall (B)

　　9. Oh, I’m not feeling well in the stomach, I ___ so much fried chicken just now.

　　A. shouldn’t eat

　　B. mustn’t have eaten

　　C. shouldn’t have eaten

　　D. mustn’t eat (C)

　　10. I was really anxious about you. You ___ home without a word.

　　A. mustn’t leave

　　B. shouldn’t have left

　　C. couldn’t have left

　　D. needn’t leave (B)