1 情態(tài)動(dòng)詞的語(yǔ)法特征
1） 情態(tài)動(dòng)詞 除ought 和have 外，后面 不定式。
2） 情態(tài)動(dòng)詞沒(méi)有 的變化。
2 比較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不表示過(guò)去時(shí)態(tài),提出委婉的請(qǐng)求，（注意在回答中不可用_________）。
--- Could I have the television on? --- Yes, you ____. / No, you _______.
3 比較may和might
1) 表示允許或請(qǐng)求；表示沒(méi)有把握的推測(cè)； He might be at home.
2) may 放在句首，表示_____。May God bless you!
3) might 表示推測(cè)時(shí)，可能性比may ____。
4）固定短語(yǔ)： may/might as well，后面接不帶to 的不定式，意為"______"。
If that is the case, we may as well try.
典型例題 ( ) Peter ___come with us tonight, but he isn't very sure yet.
A. must B. may C. can D. will
4 比較have to和must
1)兩詞都是'必須'，have to 表示____________， must 表示________________，既主觀上的必要。
My brother was very ill, so I _______ call the doctor in the middle of the night. (客觀上需要做這件事)
He said that they _____ work hard.（主觀上要做這件事）
2) 在否定結(jié)構(gòu)中： don't have to 表示"________" mustn't 表示"_______"，
You don't have to tell him about it. 你_______要把此事告訴他。
You mustn't tell him about it. 你_________把這件事告訴他。
5 must表示推測(cè)
1) must用在肯定句中表示推測(cè)，意為"________"。
2) must表對(duì)現(xiàn)在的狀態(tài)或現(xiàn)在正發(fā)生的事情的推測(cè)時(shí)， must 后面通常接________或_____________。 You have worked hard all day.You must be tired.
He must be working in his office.
比較：
He must be staying there. 他現(xiàn)在肯定呆在那里。
He must stay there. 他必須呆在那。
3) must 表示對(duì)已發(fā)生的事情的推測(cè)時(shí)，must 要接___________。
I didn't hear the phone. I must have been asleep.
4) must表示對(duì)過(guò)去某時(shí)正發(fā)生的事情的推測(cè)，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) 否定推測(cè)用 ________。
If Tom didn't leave here until five o'clock, he can't be home yet.
6 表示推測(cè)的用法 ( can, could, may, might, must 皆可表示推測(cè))，其用法如下：
1）情態(tài)動(dòng)詞+動(dòng)詞原形。
表示對(duì)現(xiàn)在或?qū)?lái)的情況的推測(cè)，此時(shí)動(dòng)詞通常為系動(dòng)詞。
I don't know where she is, she may be in Wuhan.
2）情態(tài)動(dòng)詞+動(dòng)詞現(xiàn)在進(jìn)行時(shí)。
表示對(duì)現(xiàn)在或?qū)?lái)正在進(jìn)行的情況進(jìn)行推測(cè)。
At this moment, our teacher must be correcting our exam papers.
這時(shí)，我們老師想必在批改試卷。
3）情態(tài)動(dòng)詞+動(dòng)詞完成時(shí)。
表示對(duì)過(guò)去情況的推測(cè)。
We would have finished this work by the end of next December.
明年十二月底前我們很可能已完成這項(xiàng)工作了。
The road is wet. It must have rained last night.
4）情態(tài)動(dòng)詞+動(dòng)詞的現(xiàn)在完成進(jìn)行時(shí)。
表示對(duì)過(guò)去正在發(fā)生事情的推測(cè)。
Your mother must have been looking for you. 你媽媽一定一直在找你。
5）推測(cè)的否定形式，疑問(wèn)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.
邁克一定還沒(méi)有找回他的車(chē)，因?yàn)樵缟纤亲财?chē)來(lái)上班的。
注意：could, might表示推測(cè)時(shí)不表示時(shí)態(tài)，其推測(cè)的程度不如 can, may。
7. 情態(tài)動(dòng)詞+ have +過(guò)去分詞
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 _______________(而事實(shí)上并沒(méi)有做)。
否定句表示"不該做某事而做了"。
You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.（事實(shí)上已扔了。）
ought to 在語(yǔ)氣上比should 要強(qiáng)。
4) needn't have done sth ___________________ (但是實(shí)際上已經(jīng)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…? 表示肯定含義的請(qǐng)求勸說(shuō)時(shí)，疑問(wèn)句中一般用some, 不用any。
Would you like some cake?
3）否定結(jié)構(gòu)中用will，一般不用would, won't you是一種委婉語(yǔ)氣。
Won't you sit down?
9. 情態(tài)動(dòng)詞的回答方式
問(wèn)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. 比較need和dare
這兩詞既可做實(shí)義動(dòng)詞用，又可做情態(tài)動(dòng)詞用。作為情態(tài)動(dòng)詞，兩者都只能用于疑問(wèn)句，否定句和條件句。 need 作實(shí)義動(dòng)詞時(shí)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