大学英语 情态动词2.ppt

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1、情态动词/Modal Auxiliary什么是情态动词？情态动词和助动词一样，都是辅助性的动词，用来帮助构成不同的时态和语态，表示说话者的某种情态，没有人称和数的变化may mightcan couldshall shouldwill wouldMust 无变化Will和Would1.表示请求Will you give her the letter?Would you please tell me your telephone number?2.表示习惯或倾向，与used to 进行对比Scarf used to be heavy smokerFather used not to be so

2、forgetful2.Would强调过去某种特定情况下的动作，是完全过去的事情，与现在没有联系。She used to get up at six in the morningShe would get up at six in the morningMan used to think that the earth was flatMan would think that the earth was flatIn those days,whenever I had difficulties,I_Mr.Shen for help.A.Used to go to B.Was used to go

3、toC.Would go to D.Used to going toHe_up at five,but now he gets up at six.A.Used to getting B.Would getC.Was used to get D.Used to get3.表示推测It will be Mr.Wang knocking at the door.It would be about ten oclock when he left homeThey_in New York by now.A.will arrive B.will be arrivingC.will have arrive

4、d D.are arriving4.表示命令、强迫All will arrive before 7:455.表示意愿或者固执地坚持。She wont lend me the moneyThe window wont open6.表示能力（拟人化）The hall will seat 1000 people7.表示客观事实Fish will die out of water8.表示意图或允诺You wii have your share9Would ratherWould rather(sooner).thanHe would rather_than_the secret.A.die.telli

5、ng B.die.to tellC.dead.tell D.die.tellI would rather you _her the bike the other day.A.didnt lend B.hadnt lentC.should not lend D.wouldnt have lentCan/could1）表示许可You can borrow two books at a time from the library2）表示可能性I cant guess whose book it is3）表示能力She couldnt climb the mountain注意：Cant help和co

6、uldnt bear中的不能变成be able to.The weather was able to clear upThe fire was not able to be put outCan(could)+have+过去分词有时等于may(might)+have+过去分词意思为可能Can they have missed the trainHe couldnt have been swimming all dayShe couldnt have heard you knocking at the door第二单元Have to 和 must1)have to 强调客观需要，must强调主观

7、看法I must learn another languageI have to learn another languageSomeone must have lost the game.Someone had to lose the game注意以下两句Though she didnt need to,she must go.You dont have to come again,but you must2.have to 表示义务或习惯动作，must表示重要或急迫的事情。We have to care for the youngShe has to be at the office be

8、fore eight every day.You must go to the manager at once,or youll be dismissed.3)have to 可用于不同时态，must一般只用于现在时I have to leave nowWell have to buy another TV setThey had to put off the sports meet because of the bad weather4.must可以表示推测，have to 不能This must be Jims penThere must be something wrong with t

9、he machine注意:Have to 的否定式和疑问式可以按照助动词的变化规则构成，也可以按照通用变化规则Have you to finish the work before supper?Do you have to finish the work before supperMust need 和和 need notMust not 表示禁止,所以在回答must 引导的问题时，如果否定，该怎么回答？Must needs 和和needs mustNeeds为副词,相当于necessarily,of necessity二者均可表示必须，必定，不得不，但must needs 还可以表示偏偏，偏

10、要。I must needs go there nowNeeds must when the devil drives.She must needs go away when I want her.NeedNeed可以做助动词，也可以做行为动词Father sent me the book,so I didnt need to write to him for it.Father sent me the book,so I neednt have written to him for it.She didnt need to comeShe neednt have come注意:作助动词用，n

11、eed只用于疑问句和否定句，肯定句中用must,have to,should,ought to等。Need you do it right now?I neednt,but he must.Ought toOught to没有词性变化，通用于所有人称和时态。He knew he_ tell her that.A.ought not B.ought to notC.didnt ought to D.ought not toOught to表示义务或责任，提醒某人义务或提出劝告，指出一个正确、明智的行为。Must强调主观愿望，涉及说话人的权威Have to表示由某种情况或环境所迫而不得不做的事Sh

12、ould和ought to完全相同，但ought to语气更重。You ought to respect the oldYou must do it at onceWell have to reconsider the matterWe should(ought to)do more for the countryShall1.表示征求意见或请求指示Shall we meet in the evening?How shall I start the machine?2.表示意图、意志、允诺或命令等，但shall所表示的意志是说话人的意志，并非句子主语的意志I shall give you a

13、lot of moneyEach citizen shall carry his identification card when travelling.She shall get this paper in the eveningHe shall get what he deservesShould1.用于疑问句或感叹句，表示“推断”How should I know?Why should you be worrying?2.用在Im surprised,it worries me,its a pity,its unthinkable等结构后面的句子中表示惊讶、忧虑、惋惜、欢欣等情绪。Im surprised that he should eat so little every day.Its a pity that she should fail in the entrance examination.