一、情态动词表推测
1. 肯定的推测一般用must, should, may（might）或could（不用can），其中，must的语气最强，译为“肯定”、“准是”、“想必是”；should的语气次之，译为“很可能”、“应该”，指按常理推测；may（might），could的语气最弱，译为“也许”、“可能”。
①Helen _______ go on the trip with us but she isn’t quite sure yet. 2005年安徽卷）
A. shall B. must C. may D. can
②—I’ve taken someone else’s green sweater by mistake.
—It ___ Harry’s. He always wears green. （2005年广东卷）
A. has to be B. will be C. mustn’t be D. could be
③I have lost one of my gloves. I _______ it somewhere.（2005年北京春季卷）
A. must drop B. must have dropped
C. must be dropping D. must have been dropped
④If I ____ plan to do anything I wanted to ,I’d like to go to Tibet and travel through as much of
it as possible. （2005年湖北卷）
A. would B. could C. had to D. ought to
2. 否定推测分为两种情况： 1）语气不很肯定时，常用may not, might not或could not，译为“可能不”、“也许不”。
You might just as well tell the manufacturer that male customers ______ not like the design of the furniture. （2004年上海春季卷）
A. must B. shall C. may D. need
2）否定语气较强时，则用can’t，译为“根本不可能”、“想必不会”，表示惊异、怀疑的感情色彩。
①—Do you know where David is? I couldn’t find him anywhere.
—Well. He ______ have gone far——his coat’s still here.（2005年湖北卷）
A. shouldn’t B. mustn’t C. can’t D. wouldn’t
②— Isn’t that Ann’s husband over there?
— No, it _______ be him I’m sure he doesn’t wear glasses. （2004年全国卷Ⅰ）
A. can’t B. must not C. won’t D. may not
3. 疑问句中的推测，往往用can或could。
Mr. Bush is on time for everything. How ______ it be that he was late for the opening ceremony？（2001年上海春季卷）
A. can B. should C. may D. must
4. 对已发生事情的肯定推测常用“must, may, might等+完成式”；否定推测常用“can, could, may, might等+完成式”。
①I was on the highway when this car went past followed by a police car. They _______ at least 150 kilometers an hour.（2005年重庆卷）
A. should have been doing B. must have been doing
C. could have done D. would have done
②He _______ have completed his work; otherwise, he wouldn’t be enjoying himself by seaside. （2005年北京卷）
A. should B. must C. wouldn’t D. can’t
③—Tom is never late for work. Why is be absent today?
—Something ________ to him. （2005年江西卷）
A. must happen B. should have happened
C. could have happened D. must have happened
④ My sister met him at the Grand Theatre yesterday afternoon, so he_____ have attended your lecture.（2000年上海卷）
A. couldn’t B. needn’t C. mustn’t D. shouldn’t
二、“情态动词+完成式”
1. “should（ought to）+完成式”表示本应该做某事而实际上没有做。其否定式表示某种行为不该发生但却发生了。
①—I’ll tell Mary about her new job tomorrow.
— You________ her last week. （2004年福建卷）
A． ought to tell B． would have told
C． must tell D． should have told
②Oh, I’m not feeling well in the stomach, I _____ so much fried chicken just now. （2002年上海春季卷）
A. shouldn’t eat B. mustn’t have eaten
C. shouldn’t have eaten D. mustn’t eat
2. “could+完成式”表示本来能够做成某事的但结果没能做成，含有遗憾的意味。
He paid for a seat, when he ______ have entered free. （2005年山东卷）
A. could B. would C. must D. need
3. “needn’t+不定式的完成式”表示本来不必做某事而实际上做了某事。例如：
You needn’t have watered the flowers, for it is going to rain.你本不需要浇花的，因为天就要下雨了。
— Catherine, I have cleaned the room for you.
— Thanks. You ______ it. I could manage it myself. （2005年福建卷）
A. needn’t do B. needn’t have done C. mustn’t do D. shouldn’t have done
三、常见的情态动词
1. shall用于一、三人称疑问句表示征求对方意见；用于二、三人称陈述句表示说话人给对方的命令、警告、允诺或威胁等。
①“The interest be divided into five parts, according to the agreement made by both sides，” declared the judge. （2004年重庆卷）
A. may B. should C. must D. shall
②—Excuse me, but I want to use your computer to type a report.
— You ______ have my computer if you don’t take care of it. （2004年湖南卷）
A. shan’t B. might not C. needn’t D. shouldn’t
③ — The room is so dirty. ______ we clean it?
— Of course. （2003年北京春季卷）
A. Will B. Shall C. Would D. Do
2. must用于疑问句，表示责备、抱怨的感情色彩，意思为“偏偏，偏要”；mustn’t表示禁止，是说话人强有力的劝告。
①John, look at the time. _______ you play the piano at such a late hour？ （2005年全国卷Ⅲ）
A. Must B. Can C. May D. Need
②Tom, you leave all your clothes on the floor like this！(2005年全国Ⅰ）
A. wouldn’t B. mustn’t C. needn’t D. may not
3. needn’t表示“没有必要”。
— Lucy doesn’t mind lending you her dictionary.
— She ______. I’ve already borrowed one. （2005年湖南卷）
A. can’t B. mustn’t C. needn’t D. shouldn’t
4. would表示过去反复发生的动作或某种倾向。
When he was there, he ___ go to that coffee shop at the corner after work every day.（1996年上海卷）
A. would B. should C. had better D. might
5. 表示经过努力而成功的某一次动作，只能用was/were able to，而不能用could。
The fire spread through the hotel very quickly but everyone _____ get out. （1997年全国卷）
A. had to B. would C. was able to D. could
6. 考查情态动词用作答语的情况
①—Write to me when you get home.
— _______. （2001年北京春季卷）
A. I must B. I should C. I will D. I can
② — Could I call you by your first name？
—Yes, you ______. （1998年上海卷）
A. will B. could C. may D. might
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