英语情态动词总结.doc

情态动词1、情态动词的基本用法 (1)can、could 和be able tocan和couldcan和could表示: 1)能力、技能（理论上）2)请求、允许（肯定回答只能用can,不能用could）3)可能性（理论上） The road can/may be blocked. 区别？could比较委婉客气，回答时则用can。如： Could you help me carry the bag? Yes, I can.can和be able to都表示能力，区别为：can只有现在和过去时，而be able to则有更多的形式，如will be able tocan表示理论上的，一般的能力；成功地完成某一具体动作时，用be(was/were) able to。这时was/were able to 相当于managed to，表示经过一番努力，终于能够完成某事。如： Can you use chopsticks?The wounded man still was able to get to the village and was saved in the end.(2) may/mightmay/might表示：1)可能性 （may比might可能性大）2)允许,请求（might表示比较委婉的语气，回答用may） May / Might I use your bike?Yes, you can / may.No, you mustnt3)祝愿 may+主+谓（动词原形）May you succeed.=Wish you success.（3）mustmust表示:1)必须，应该 You must do everything as I do. -Must? -Yes, you must. / No, you neednt. No, you dont have to.2)肯定的推测 The light is still on, so he must be at home.3)mustnt 表示禁止做某事 You mustnt smoke in the office.（4）have tohave to 表示“必须、不得不”，是由于某种外界（客观）原因而“必须”，“不得不”做某事。dont have to表示不必。have to可用于多种时态中。如： You will have to clean your own boots when you join the army. I have to be at my office every evening.（5）should / ought toshould和ought to表示:1)应当、应该 前者比后者语气轻 2)否定形式表示禁止 Children shouldnt smoke.3)劝告 You ought to respect your parents.Should:1)第一人称委婉语气：I should think it would be better to try it again. 我倒是认为 2)if条件句中，万一：Ask her to ring me up if you should see her. 3)竟然4)推测（按理来说）must和have to的区别？must和should/ought to的区别？（6）will / wouldwill/would表示：1)意志、意愿、决心 否定式wont, if I will2)请求、询问 (常用在第二人称时表示说话人向对方) Will/Would you please tell her the news when you see her?3)will 表示习惯性的动作 Fish will die out of water.would 表示过去反复发生的动作 When I passed my school I would see my teachers who taught me 5 years ago.（7）needneed 作“必要”讲，既可作情态动词，也可作实义动词。作实义动词时后面的动词不定式要带to，其变化与一般动词相同。如： I need to think it over.Need you go now? Yes, I must. /No, I neednt.（8）daredare表示“敢”的意思。作为情态动词时，主要用在疑问句和否定句中。有过去式dared。dare若作实义动词，后面可带to的不定式，此时to也可以省略。dare与need的用法相似。如： How dare you say that? She doesnt dare(to)ask her father.（9）used toused to表示过去常常发生的动作或存在的习惯，但现在已不复存在了。如： He used to smoke.（10）shallshall表示：1）用于二、三人称，表示说话人的意愿，有“命令”、“警告”、“威胁”、“强制”、“允许”等意思。如：1You shall pay for this. 你要为此付出代价。（threat）2You shall have a car for your birthday. 你过生日会得到一辆汽车。（promise）3 When he comes in nobodyshall say a word.他进来的时候，谁也不许说话。（command）4Sorry, sir. But it is the management rules of our hotel that payment shall be made in cash.对不起，先生，我们酒店规定（顾客）得付现金。(regulation)5Its getting dark. Shall I turn on the light? 天黑了，我把灯打开好吗？(request)2)用于第一、第三人称,征求对方的意见或请求。如： Where shall he wait for us? Shall we go out for a walk?3)用于法律、法令或正式文件。如：The fine should be paid in cash.2、情态动词表示推测或判断的用法下表即是表示推测的情态动词使用的场合：情态动词 对现在和未来的推测 对过去的推测 Must must + 动词原形 must have done may / might may / might + 动词原形 May / might have done can /could can / could do can / could have done例如：(1) can:表可能性多用于否定与疑问结构中，但也可用在肯定句中。Can the news be true? 这消息可能是真的吗？It cant be true. 它不可能是真的。What can he possibly mean? 他可能是什么意思？can 用在肯定句中表示理论上的可能性（一时的可能）。A horse in the center ofLondoncan cost a lot of money.Attending the ball can be very exciting.The road can be blocked. 这条路可能会不通的。Could表过去的可能和许可 。（多用于间接引语中）At that time we thought the story could not be true.那时我们认为所说的事不可能是真的。Father said I could swim in the river.爸爸说我可以在河里游泳。Could/can have done 结构表示对过去发生的事情的“怀疑”或“不肯定”。 Can they have won the basketball match？他们赢了那场篮球赛吗？What you referred to just now can have made her very sad.你刚刚所谈到的可能令他很伤心。You could have completed the task a little earlier.你本来能早点完成任务的。（但事实上并没有提前完成任务）I could have passed my examination easily but I made too many stupid mistakes.我本可以轻易通过考试，但我犯了太多不该犯的错误。(2)may 在肯定句中表示现实的可能性。The road may be blocked. 这条路可能不通了。may /might 推测性用法 可能He may be right.He may not come today. (可能不)He may /might come tomorrow.注意 : (1)只用于肯定和否定句中,不用于疑问句中。（2）might 比may可能性更小 (3) may no 可能不 can not不可能may (might) have done 表示对过去发生行为的推测，含有“想必”、“也许是”的意思。It may have been true. 这事也许是真的。He might not have settled the question. 他可能尚未解决那个问题。It must have rained last night.They should be there right now.3、情态动词在虚拟语气中的用法（1）should have done表示“本来应该做某事而实际上未做” ought to have doneshouldnt have done表示“本不应该做某事而实际上做了” oughtnt to have doneYou should have told me about it earlier.You shouldnt have said such words to your parents.（2）neednt have done表示“本无必要做某事而实际上做了”You neednt have walked so quickly since time was enough.（3）could have done表示“本来有可能,可以而事实上未做到”I could have come on time, but my car broke on the way.四：情态动词+行为动词进行式情态动词+行为动词进行式（即情态动词+ be + v.-ing形式），表示推测或评论某动作现在是否正在进行。例如：1）He must be playing basketball in the room.2）She may be staying at home.五.情态动词+行为动词完成进行式情态动词+行为动词完成进行式（即情态动词+ have been + v.-ing 形式），表示推测或评论过去某动作是否正在进行或一直在进行。例如：1）They should have been meeting to discuss the problem.2）He may / might have been buying stamps in the post office when you saw him.六.used to +v., be used to +v.-ing和be used to +v.（1）used to +v.“过去常常”，“过去一直”；be used to +v.-ing / n.（名词）“习惯于”；be used to +v.“被用来（做某事）”。（2）used to只表示过去，而be used to +v.-ing / n可表示现在、过去或将来。例如：1）He used to smoke. Now he doesnt.2）Hes quite used to hard work / working hard.3）The knife is used to cut bread.七用作情态动词的其他短语would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情态动词。例如：1）The soldier would sooner die than surrender.2）The brave soldier would as soon die as yield to such an enemy.3）Id rather walk than take a bus.4）If you dont like to swim, you may just as well stay at home.注：这些短语后一般直接跟动词原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句，that 常省去，从句要用虚拟语气。对现在和