1 情态动词的语法特征
1） 情态动词 除ought 和have 外，后面 不定式。
2） 情态动词没有 的变化。
2 比较can 和be able to
1）表示成功地做了某事，只能用_____________。
He was able to flee Europe before the war broke out.
= He managed to flee Europe before the war broke out.
2) could不表示过去时态,提出委婉的请求，（注意在回答中不可用_________）。
--- Could I have the television on? --- Yes, you ____. / No, you _______.
3 比较may和might
1) 表示允许或请求；表示没有把握的推测； He might be at home.
2) may 放在句首，表示_____。May God bless you!
3) might 表示推测时，可能性比may ____。
4）固定短语： may/might as well，后面接不带to 的不定式，意为"______"。
If that is the case, we may as well try.
典型例题 ( ) Peter ___come with us tonight, but he isn't very sure yet.
A. must B. may C. can D. will
4 比较have to和must
1)两词都是'必须'，have to 表示____________， must 表示________________，既主观上的必要。
My brother was very ill, so I _______ call the doctor in the middle of the night. (客观上需要做这件事)
He said that they _____ work hard.（主观上要做这件事）
2) 在否定结构中： don't have to 表示"________" mustn't 表示"_______"，
You don't have to tell him about it. 你_______要把此事告诉他。
You mustn't tell him about it. 你_________把这件事告诉他。
5 must表示推测
1) must用在肯定句中表示推测，意为"________"。
2) must表对现在的状态或现在正发生的事情的推测时， must 后面通常接________或_____________。 You have worked hard all day.You must be tired.
He must be working in his office.
比较：
He must be staying there. 他现在肯定呆在那里。
He must stay there. 他必须呆在那。
3) must 表示对已发生的事情的推测时，must 要接___________。
I didn't hear the phone. I must have been asleep.
4) must表示对过去某时正发生的事情的推测，must 后面要接不定式的_____________。
---Why didn't you answer my phone call?
---Well, I must have been sleeping, so I didn't hear it.
5) 否定推测用 ________。
If Tom didn't leave here until five o'clock, he can't be home yet.
6 表示推测的用法 ( can, could, may, might, must 皆可表示推测)，其用法如下：
1）情态动词+动词原形。
表示对现在或将来的情况的推测，此时动词通常为系动词。
I don't know where she is, she may be in Wuhan.
2）情态动词+动词现在进行时。
表示对现在或将来正在进行的情况进行推测。
At this moment, our teacher must be correcting our exam papers.
这时，我们老师想必在批改试卷。
3）情态动词+动词完成时。
表示对过去情况的推测。
We would have finished this work by the end of next December.
明年十二月底前我们很可能已完成这项工作了。
The road is wet. It must have rained last night.
4）情态动词+动词的现在完成进行时。
表示对过去正在发生事情的推测。
Your mother must have been looking for you. 你妈妈一定一直在找你。
5）推测的否定形式，疑问形式用can't, couldn't表示。
Mike can't have found his car, for he came to work by bus this morning.
迈克一定还没有找回他的车，因为早上他是坐公共汽车来上班的。
注意：could, might表示推测时不表示时态，其推测的程度不如 can, may。
7. 情态动词+ have +过去分词
1) may(might) have + done sth, can (could) have + done sth ____________________。
Philip may (might) have been hurt seriously in the car accident.
Philip can (could) have been hurt seriously in the car accident.
2) must have +done sth，___________________。
--- 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 _______________(而事实上并没有做)。
否定句表示"不该做某事而做了"。
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。）
ought to 在语气上比should 要强。
4) needn't have done sth ___________________ (但是实际上已经做了)
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
I would like to have read the article, but I was very busy then.
8. will和would
注意：
1）would like sth；Would like to do = want to 想要做---。 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, 不用any。
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。
Won't you sit down?
9. 情态动词的回答方式
问句 肯定回答 否定回答
Need you…? Yes, I must. No,I needn't
Must you…? /don't have to.
10. 比较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，两者都只能用于疑问句，否定句和条件句。 need 作实义动词时后面%B
-No, you ______ . I've told him already.
A. needn't B. wouldn't
C. mustn't D. shouldn't
6. ─There were already five people in the car but they managed to take me as well.
─ It______ a comfortable journey.
A. can't be B. shouldn't be
C. mustn't have been D. couldn't have been
7. It's nearly seven o'clock. Jack______ be here at any moment.
A. must B. need C. should D. can
8. .When he was there, he______ go to that coffee shop at the corner after work
every day.
A. would B. should C. had better D. might
9. .Sir, you _____ be sitt even though he was very busy.
A. might have given B. might give C. may have given D. may give
2. Jenny______ have kept her word. I wonder why she changed her mind.
A. must B. should C. need D. would
3. . -Could I borrow your dictionary?
-Yes, of course you_________
A. might B. will C. can D. should
4. 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
5. -Shall I tell John about it?
-No, you ______ . I've told him already.
A. needn't B. wouldn't
C. mustn't D. shouldn't
6. ─There were already five people in the car but they managed to take me as well.
─ It______ a comfortable journey.
A. can't be B. shouldn't be
C. mustn't have been D. couldn't have been
7. It's nearly seven o'clock. Jack______ be here at any moment.
A. must B. need C. should D. can
8. .When he was there, he______ go to that coffee shop at the corner after work
every day.
A. would B. should C. had better D. might
9. .Sir, you _____ be sitting in this waiting room. It is for women and children only.
A. oughtn't to B. can't
C. won't D. needn't
10. The fire spread through the hotel very quickly but everyone ______ get out.
A. had to B. would C. could D. was able to