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
Key: C D B B
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
Key： C
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
Key: C A
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
Key：A
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_____your lecture.（2000年上海卷）
A. couldn’t have attended
B. needn’t have atterded
C. mustn’t have attended
D. shouldn’t have attended
Key: B B D A
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
Key: D C
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
Key：A
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
Key: B
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
Key: D A B
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年全国卷Ⅰ）
A. wouldn’t B. mustn’t
C. needn’t D. may not
Key: A B
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
Key: C
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
Key: A
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
Key：C
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
Key：C C
巩固练习：
1. Michael ______ be a policeman, for he is much too short.
A. needn’t B. can’t
C. should D. may
2. I told Sally how to get here, but perhaps I ____ for her.
A. had to write it out
B. must have written it out
C. should have written it out
D. ought to write it out
3. Jack _____ yet, otherwise he would have telephoned me.
A. mustn’t have arrived
B. shouldn’t have arrived
C. can’t have arrived
D. needn’t have arrived
4. Sir, you ______be sitting in this waiting room. It is for women and children only.
A. mustn’t B. can’t
C. won’t D. needn’t
5. 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
6. — Is John coming by train?
— He should, but he _____ not. He likes driving his car.
A. must B. can
C. need D. may
7. It has been announced that candidates _______ remain in their seats until all the papers have been collected.
A. can B. will
C. may D. shall
8. You can’t imagine that a well-behaved gentleman ______ be so rude to a lady.
A. might B. need
C. should D. would
9. —Don’t forget to come to my birthday party tomorrow.
—_______.
A. I don’t B. I won’t
C. I can’t D. I haven’t
10. I didn’t see her in the meeting-room this morning. She ______ at the meeting.
A. mustn’t have spoken
B. shouldn’t have spoken
C. needn’t have spoken
D. couldn’t have spoken
答案与解析
1. B 从第二个分句“他太矮了”可以推知说话者持否定态度，needn’t意思是“没有必要”，与语境不符。
2. C 根据句意“我已经告诉她怎样到那儿，但是或许我应该给她写下来”可知，说话者含有“后悔、遗憾”的意味，应使用“情态动词+完成式”形式，“must+完成式”表示对过去的肯定推测，“should+完成式”才表示虚拟意义。
3. C 根据第二分句“否则的话他就会给我打电话了”可知“Jack肯定还没到”，“can’t+完成式”意思是“根本不可能”。
4. A 从第二分句可知，这是妇女和儿童专用候车室，因此你“不准”坐在这儿。mustn’t表示“禁止，不准”。
5. B can在此表示许可。
6. D 从后一句“他喜欢开车”可知说话者把握不大。must not不表示推测，can not的语气太绝对，意思是“根本不可能”。
7. D shall用于第二、三人称，表示说话人给对方的命令、警告、允诺、威胁等意思。
8. C should在此表示惊讶的感情色彩，意思是“竟然”。
9. B 对祈使句的肯定回答用I will；否定回答用I won’t。
10. D 根据句意“我今天上午在会议室没见到她”， 所以“她根本不可能在会上发言”。表示“根本不可能”用can’t/couldn’t have done形式。
