中考复习专题 情态动词

专题八情态动词情态动词本身有一定意义，表允诺、愿望、义务、命令和猜测。

它必须和动词原形一起构成谓语。

情态动词没有人称和数的变化。

把情态动词放在句首、句尾用问号便构成疑问句；在其后加上not或never 等否定词就构成否定句。

一、常见情态动词的用法（一）can/ could的用法1.表示具备某种“能力”，但不一定做事情，仅仅表示有能力而已。

could是can的过去时：Can you swimacross the river?你能游过那条河吗？2.表示“请求”（疑问句中）、“允许”。

Could 比Can委婉；两者都指现在。

回答一律用can, may或ofcourse,否定用mustn't。

3.表示“可能性”，都可以表示现在和将来，只是could的语气更加不肯定。

否定式表示“不可能”，如：Theycan't/ couldn't be doing that now.（二）may/ might的用法1.表示允许或请求允许，might语气更委婉。

肯定回答用may/ might/ can，否定回答用may not, can't,mustn't.──May I turn on the TV?页 1 第──Yes, you may/ can.(No, you can't/ mustn't.)2.表示可能性，“也许”。

这时may和might 表现在，只是might在语气上更不肯定一些。

如：You may/ might have some fever.表示可能性时，may/ might不用于疑问句，可用can/could或别的说法。

如：Is it likely to rain?3.祈使句中表示祝愿：May you succeed! （三）must的用法1.表示义务、命令或劝告，“必须”。

You must tell methe truth.你必须和我说实话。

在回答由must引起的问题时，否定回答用needn't或don't have to,表示“不必、没必要”；而mustn't表示“不准许”的意思。

──Must the ladies wear dresses? ──No, they don't have to / they needn't.2.表示推测，“肯定”。

此时，must只用于肯定句。

在否定句或疑问句中，用can/ could：There must be a mistake. Can / Could there bea mistake?（四）need和dare的用法情态动词need“需要”和dare“敢”通常只用于否页 2 第定句和疑问句中。

You need not come so early. How dare you be sorude?但need和dare可作为实义动词，后跟动词不定式，可用在所有句型中，注意此时他们的否定式和疑问式与情态动词不同。

（五）shall和will的用法1.shall用在第一、三人称作主语的疑问句中，来征求意见。

Shall I go now? Shall we invite her, too?2.shall用于所有人称，表示说话人的决心、保证、许诺、威胁、警告、命令等强烈的感情，如：You shallhave an answer by tomorrow. He shall suffer forthis.3.will可以表示“愿意、肯、会、固执”等意义，而非将来，would则更婉转：I will pay for it. We'regoing on a climbing trip. Come if you would.4.will可以表示倾向、习惯，在否定句中可以表示“不肯、不能”等意思：Oil and water will not mix. This machine won'twork.5.would可以表示过去的习惯，类似used to：He would come to see me on Sunday when he was here.页 3 第（六）should / ought to的用法两者大多数情况下可以互换。

Ought to 的否定式为ought not to / oughtn't to 。

1.表示道义上的责任，义务或要求，有时表示劝告，“应该”，如：You ought to / should pay more attention to whatyour teacher says.2.表示对现在和将来的推测：This pen ought to/should be yours.3.“should/ ought to have+过去分词”表示对过去的推测，“应该已经”。

有时表示“本应该做而没有做”；“should not/ ought not to have+过去分词”表示“做了不应该做的事情”，是“本不该”的意思，因而它们都含有责备的语气：He began two hours ago.He ought to have finished filling inthe formsnow. You should not have asked him for help.4.表示讲话人惊奇，失望，愤怒等感情：Why shouldI believe you? What's happened to that money?How should I know?（七）had better表示“最好……”，后接动词原形，其否定式为had better not+ 动词原形would rather意思是“宁愿”，表示选择。

它有两种用法：页 4 第一是在肯定句中后边直接跟动词原形，其否定句是在would rather后加not，即：would rather not+动词原形；二是它后边可以接从句，该从句的谓语动词用一般过去式表示虚拟语气。

由于would rather表示选择，它后边可接than。

二、情态动词+ have+ done（一）must have done表示对过去的推测，意思是“一定已经，想必已经，准是已经……”，只用于肯定句中。

The streets are wet. It must have rained.街道是湿的，准是下雨了。

否定要用“can't/ couldn't+have+过去分词”，意思是“不可能”：The pocketcan't have been lost there.（二）may/ might have done表示对过去的推测，意思是“也许已经……，可能已经……”。

用于肯定或否定句中。

疑问句中用can或could.此外，“might have+过去分词”也表示“本来可以……但没有实现”的意思，含有责备的口气。

例如：He may have gone to bed. You might havetold me earlier.你本可以早点告诉我的。

（埋怨责备）（三）needn't have done页 5 第“needn't +have+过去分词”表示“本来不需要做”，“做了不必做或不需要做的事”，如：I needn't haveborrowed the money yesterday.注意didn't needto do表示“没有必要做而实际上也没有做某事”。

（四）：can/ could have done:用来谈过去的情况1.在疑问句、否定句中，表示对过去的行为的怀疑和不可能，这时它们没有时间上的差别，只是could的语气更弱一些：Who could have taken them? Hecan't have taken it home.2.could have done在肯定句中，表示“那时本来可以……；差点就要……”，有时用来进行婉转地批评：He could have told her, but he did not choose to. （五）should/ ought to have done表示“过去应该做某事却没有做”；“should not/ought not to have+过去分词”表示“做了不应该做的事”。

含有责备或遗憾的意思：You should have comehere ten minutes earlier.三、几组情态动词用法的区别（一）can和be able to的区别。

在一般将来时和现在完成时中只能用be able to。

can表示具备某种能力，但不一定做事；而be able to表示后天努力设法去做，成功后说明有能力，如：He was able to swim 页 6 第across the river in fifteen minutes.(= He managedto swim across the river in fifteen minutes.)（二）must与have tomust强调主观意志，必要性来自说话者的主观意志，“必须”。

Have to强调客观因素，“不得不”。

如：Hemust stop smoking.他必须戒烟。

（说话人认为他必须）You have to go and see the boss.你一定得去见见老板。

（客观因素）注意：must not表示“绝对不可”；don't have to（或haven't got to）表示“不必，没必要”，两者意思极为不同。

（三）would与used towould可表示反复发生的动作或某种倾向。

Used to表示过去的习惯动作或状态，强调现在已不存在。

如：She used to work into the night.过去她常工作到深夜。

（现在不了）She would work into the might.以前她常工作到深夜。

（不表示现在不了）【例题精析】例1. Tom, you ______ leave all your clothes onthe floor like this!页 7 第A.wouldn'tB.mustn'tC.needn'tD.may not答案：B 。

例2. Where is my pen? I _____ it.A.might loseB. need have lostC. must loseD. must have lost答案：D 。

专题测试1.──Could I borrow your book?──Yes, of course you ______ . A. may B. could C. must D. can2. I wonder how he that _______ to his parents.A. dare to sayB. dared sayC. dares to sayD. didn't dare to say3.──Shall I tell him about it?──No, you ______ . I have told him already.A. needn'tB. wouldn'tC. shouldn'tD. mustn't4. I _______ have written to him because he phonedme later.A. ought toB. mustC. couldn'tD. needn't5.──You can hardly swim, can you?页 8 第── _______ . But my mother said she wouldteach me.A. Yes, I can'tB. No, I can'tC. No, Ican D. Yes, I can6.──Write to me when you get home. ── ______ .A.I mustB.I shouldC.I willD.Ican7.─Where shall we meet tomorrow?─Well.I ____come to your house if you like.A. couldB. mightC. shouldD. must8. Don't throw the bottles away. They_____ inthe future.A. may needB. are neededC. canbe needingD. might be needed9. He was caught in the rain last night. That_____ his cold.A. must bring aboutB. ought tobring aboutC. should have brought aboutD. may havebrought about10.──I saw Jane in the street yesterday.──You _______ her. He is still abroad.页 9 第A. mustn't seeB. can'thave seenC.mustn't have seenD.ought not to have seen11.──You must phone us every week.──Yes, I _____ .A. mustB. have toC. willD. should12. John, look at the time. _______ you play thepiano at such a late hour?A. MustB. CanC. MayD. Need13. The line is busy. Someone _____ thetelephone.A. may be usingB. may have usedC. musthave been using D. must be using 14. English is a language that many people aroundthe world ____ not speak perfectly butat least_____ understand.A. may, canB. would, mightC. will, mustD. could, might15.──What are you going to do for your holiday?──I'm not sure. I _____ make atrip to thebeach.A. canB. mayC. mustD.页 10 第should16.──I wonder why Mr. Wang didn't attend thelecture.──He ______ another one.A. could haveB. must haveC. might have hadD. should have had17. He was taken away by the police. He______for a robber.A. must be mistakenB. was beingmistakenC. must mistakeD.must have beenmistaken18.──Must I be at home at 6 ?──No, you _____ .A. mustn'tB. can'tC. needn'tD.shouldn't19.──I wonder if I ______ smoke here.──No, you ______ . Could you see the sign“No Smoking”there?A. can, needn'tB. shall, won'tC. must,can't D. may, mustn't20. Tom always did well in all his subjects, so页 11 第he ______ in the final exam.A. mustn't failB. couldn'thave failedC. ought not to failD. mustn't havefailed21.──I didn't go to work yesterday afternoonbecause my car broke down.──You ______ mine. I wasn't using it.A. might borrowB. could have borrowedC.can have borrowed D. ought to borrow 22. A computer ________ think for itself, it mustbe told what to do.A. can'tB. couldn'tC. may notD. might not23. I didn't hear the phone. I ______ asleep.A. must beB. must have beenC. should beD. should have been24. We _______ last night, but we went to theconcert instead.A. must have studiedB. might studyC. shouldhave studied D. would study25. Tom ought not to ______ me your secret, but页 12 第he meant no harm.A. have toldB. tellC. be tellingD.having told26.──I haven't seen Mr. White for weeks.──What _______ to him?A. must have happenedB. may havehappenedC. can have happenedD. may happen27. The fire spread through the hotel veryquickly but everyone ______ get out.A. had toB. wouldC. couldD. wasable to28.──Will you stay for lunch?──Sorry, ______ . My brother is coming tosee me.A. I mustn'tB. I can'tC. Ineedn'tD. I won't29. I was really anxious about you.You ______home without a word.A. mustn't leaveB. shouldn't haveleft C.couldn't have left D. needn't leave 30.──I hear you've got a set of valuable页 13 第Australian coins. _____ I have a look?──Yes, certainly.A. DoB. MayC. ShallD. Should页 14 第。