《专四情态动词》PPT课件.ppt

Special VerbsAuxiliaries&Modal Words,情态动词,Grammar,CONTENT,Review:Auxiliaries,Differences among modals,Difficult Points,Modals Expressing Prediction and predictability,Modals+have+-en participle,Grammatical Features：,Grammar,Review:Auxiliaries,The grammatical function of auxiliaries is to help main verbs.Auxiliaries fall into three categories:primary auxiliaries,modal auxiliaries and semi-auxiliaries.助动词的语法功能是协助主动词表示不同的语法意义或情态意义,比如表示某一动作正在进行或已经完成，“应该”做某事或“不应该”做某事。助动词分为三类：基本助动词、情态助动词和半助动词。,Grammar,Primary Auxiliary,There are three primary auxiliaries:be,do,have.With no lexical meanings of their own,these auxiliaries have only grammatical functions or grammatical meanings.基本助动词只有三个：be,do,have。作为助动词，be,do,have本身没有词汇意义，只在动词词组中起语法作用或者说只表示语法意义。比如助动词be经常用来协助主动词构成进行体或被动态。,Grammar,Modal Auxiliaries,There are thirteen modal auxiliaries including some past tense forms.They are:can/could,may/might,will/would,shall/should,must,ought to,dare,need,used to.情态助动词一共有13个，其中包括一些过去时形式。它们是：can/could,may/might,will/would,shall/should,must,ought to,dare,need,used to.情态动词表示情态意义，其过去时形式并不一定就表示过去时间。情态动词不能重叠使用；随后的主动词无一例外地是不带to的不定式即动词原形。,Grammar,情态助动词的“时”的形式和意义,如前所述，情态助动词共有九个，或者说总共有十三个。其中四个各有现在时和过去时两种形式（即may/might,can/could，will/would,shall/should），其余的或者只有现在时形式而无过去时形式（即must,ought to,need,dare），或者只有过去时形式而无现在时形式（即used to）。在上述情态助动词中，dare（敢）和need（需要）也能作主动词用。比较：He dare not come.(作情态动词用)He doesnt dare to come.(作主动词用)Need he study?(作情态动词用)Does he need to study?(作主动词用),Grammar,另有一个used to（过去经常）虽然不能作主动词用，但其否定形式既可以是 used not to，也可以是 did not use to等。因此，有的语法学家把上述三个情态助动词称为“边际情态助动词”（Marginal Modal Auxiliary）。,情态助动词的“时”的形式和意义,Grammar,情态助动词的“时”的形式和意义,如前所述，情态助动词的“时”的形式并不是时间区别的主要标志，就是说，现在时或过去时形式有时是时间区别的标志，有时却又不是，而且可以说多半不是。例如：Can you lift that table？你能举起那张桌子吗？Could you lift that table when you were younger？你年轻一些的时候能举起那张桌子吗？Can/could在这两例中的时间区别是显而易见的，前者指现在时间，后者指过去时间。但是，can/could在下列两例中并不表示时间区别，而只有语气上的差异：Can you help me,please？请你帮帮我好吗？Could you help me,please？请你帮帮我好吗？,Grammar,情态助动词的“时”的形式和意义,以上是就直接引语（Direct Speech）的通常情况而言。在间接引语（Indirect Speech）中，如果引述动词为过去时形式，通常的情况是：第一，如果所用的情态助动词有过去时形式，根据时间向过去推移的原则，需将现在时形式改为过去时形式。例如：“It may rain”可能会下雨。We were afraid it might rain“You can help me carry the cases”你们能够帮我携带这些箱子。He said that we could help him carry the cases“The plan will fail”这计划不会成功。I warned them that the plan would fail“Shall I open the window？”我可以把窗打开吗？He wondered whether he should open the window,Grammar,情态助动词的“时”的形式和意义,如果在直接引语中已经用了情态助动词的过去时形式，间接引语中情态助动词形式不变，不过，时间关系应理解为是向过去作了推移。例如：“Would you like a cup of tea？”来杯茶好吗？He asked if I would like a cup of tea,Grammar,情态助动词的“时”的形式和意义,第二，如果所用情态助动词无过去时形式，在间接引语中则仍采用现在时形式，不过，时间关系应理解为是向过去作了推移。例如：“You must reach camp by ten”你们必须10点钟以前到达营地。They were told they must reach camp by ten“You ought to be ashamed of yourself”你应该为自己感到害臊。He told me I ought to be ashamed of myself,Grammar,情态助动词的“时”的形式和意义,must和need这两个情态助动词，根据所用人称以及是否用于肯定陈述句、否定陈述句、疑问句等情况，在变为间接引语时也可作其他变动。通常是：（I）must must/had to/would have to（I）must not must not Must（I）had to（YouHe）mustmust（YouHe）must notmust not/werent to，wasnt toMust（youhe）had to（Iyouhe）neednt neednt/didnt have towouldnt have toNeed（Iyouhe）needhad to,Grammar,情态动词的语法特征,1）情态动词不能表示正在发生或已经发生的事情，只表示期待或估计某事的发生。2）情态动词 除ought 和have 外，后面只能接不带to 的不定式。3）情态动词没有人称，数的变化，即情态动词第三人称单数不加-s。4）情态动词没有非谓语形式，即没有不定式，分词，等形式,Grammar,比较can 和be able to(P.238),1）cancould 表示能力；可能(过去时用could),只用于现在式和过去式(could),be able to可以用于各种时态。They will be able to tell you the news soon.他很快就能告诉你消息了。2）只用be able to a.位于助动词后。b.情态动词后。c.表示过去某时刻动作时。d.用于句首表示条件。e.表示成功地做了某事时，只能用was/were able to，不能用could,Grammar,比较can 和be able to(P.238),He was able to flee Europe before the war broke out.=He managed to flee Europe before the war broke out.注意：could不表示时态1）提出委婉的请求，（注意在回答中不可用could）。-Could I have the television on?-Yes,you can./No,you cant.2）在否定，疑问句中表示推测或怀疑。He couldnt be a bad man.他不大可能是坏人。,Grammar,比较can 和be able to(P.238),be able to 表示在特定情景中努力做成某事。The first spread through the building very quickly,but luckily everyone was able to escape.大火在楼里蔓延，幸好大家都及时撤离了。（在此不能用could）They didnt want to come with us at first,but in the end we were able to persuade them.起初他们不想与我们一起来，但是最后我们还是说服了他们。（在此不能用could）,Grammar,比较may和might(P242),1）表示允许或请求；表示没有把握的推测；may 放在句首，表示祝愿。May God bless you!He might be at home.注意：might 表示推测时，不表示时态。只是可能性比may 小。2）成语：may/might as well，后面接不带to 的不定式，意为“不妨”。If that is the case,we may as well try.典型例题Peter _come with us tonight,but he isnt very sure yet.A.mustB.may C.can D.will答案B.表可能性只能用may.此句意可从后半句推出。,Grammar,比较have to和must(P244),1)两词都是必须的意思，have to 表示客观的需要，must 表示说话人主观上的看法，既主观上的必要。My brother was very ill,so I had to call the doctor in the middle of the night.我弟弟病得很厉害，我只得半夜里把医生请来。(客观上需要做这件事)He said that they must work hard.他说他们必须努力工作。（主观上要做这件事）2)have to有人称、数、时态的变化，而must只有一种形式。但must 可用于间接引语中表示过去的必要或义务。He had to look after his sister yesterday.,Grammar,3）在否定结构中：Dont have to 表示“不必”mustnt表示“禁止”，You dont have to tell him about it.你不一定要把此事告诉他。You mustnt tell him about it.你一定不要把这件事告诉他。,Grammar,must表示推测(P248),must用在肯定句中表示较有把握的推测，意为“一定”。must表对现在的状态或现在正发生的事情的推测时，must 后面通常接系动词be 的原形或行为动词的进行式You have worked hard all day.You must be tired.你辛苦干一整天，一定累了。（对现在情况的推测判断）He must be working in his office.他一定在办公室工作呢。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。,Grammar,must表示推测(P248),3)must 表示对已发生的事情的推测时，must 要接完成式。I didnt hear the phone.I must have been asleep.我刚才没有听到电话，我想必是睡着了。4)must表示对过去某时正发生的事情的推测，must 后面要接不定式的完成进行式。-Why didnt you answer my phone call?-Well,I must have been sleeping,so I didnt hear it.5)否定推测用cant。If Tom didnt leave here until five oclock,he cant be home yet.如果汤姆五点才离开这儿，他此时一定还未到家。,Grammar,would与 used to 的区别(P248),would 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。例如：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）People used to think that the sun went round the earth.以前人们总认为太阳是围绕地球转的。（现在不这样认为了）I used to smoke quite a lot,but I have given it up.我过去抽烟很凶，现在戒了。,Grammar,比较need和dare(p246),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 作实义动词时后面的不定式必须带to，而dare作实义动词用时,后面的to 时常可以被省略。1)实义动词：need（需要,要求）need+n./to do sth2)情态动词：need，只用原形need后加do，否定形式为need not。Need you go yet?Yes,I must./No,I neednt.3)need 的被动含义：need,want,require,worth（形容词）后面接doing也可以表示被动：need doing=need to be done,Grammar,will和would(P235),注意：1）would like；Would like to do=want to 想要，为固定搭配。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,而不是any。Would you like some cake?3）否定结构中用will，一般不用would,wont you是一种委婉语气。Wont you sit down?,Grammar,would rather表示宁愿,would rather dowould rather not dowould rather than 宁愿而不愿。还有would sooner,had rather,had sooner都表示“宁愿”、“宁可”的意思。If I have a choice,I had sooner not continue my studies at this school.I would rather stay here than go home.=I would stay here rather than go home.,Grammar,典型例题-Shall we go skating or stay at home?-Which _ do?A.do you ratherB.would you rather C.will you rather D.should you rather答案B。本题考查情态动词rather的用法，would rather+do sth 意为宁愿，本题为疑问句，would 提前，所以选B,Grammar,had better表示“最好”,had better 相当于一个助动词，它只有一种形式它后面要跟动词原形。had better do sth had better not do sthIt is pretty cold.Youd better put on my coat.Shed better not play with the dog.had better have done sth 表示与事实相反的结果，意为本来最好。You had better have come earlier,Grammar,should 和ought to,should 和ought to 都为应该的意思，可用于各种人称。-Ought he to go?-Yes.I think he ought to.表示要求，命令时，语气由 should（应该）、had better最好）、must（必须）渐强。,Grammar,带to 的情态动词,带to 的情态动词有四个：ought to,have to,used to,be to,如加上have got to,(=must),be able to，为六个。它们的疑问，否定形式应予以注意：Do they have to pay their bill before the end of the month?She didnt use to play tennis before she was fourteen.You ought not to have told her all about it.Ought he to see a heart specialist at once.?,Grammar,ought to 本身作为情态动词使用。其他的词作为实义动词使用，变疑问，否定时，须有do 等助动词协助。典型例题Tom ought not to _ me your secret,but he meant no harm.A.have told B.tell C.be telling D.having told答案A。由于后句为过去时，告诉秘密的动作又发生在其前因，此地应用过去完成时，但它在情态动词 ought to 后，所以用have。,Grammar,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 dont 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。,Grammar,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.地是湿的，昨天晚上一定下雨了。,Grammar,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cant,couldnt表示。Mike cant 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。,Grammar,情态动词+have+过去分词,1)may(might)have+done sth,can(could)have+done sth表示过去，推测过去时间里可能发生的事情。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，对过去时间里可能发生的事情的推测，语气较强，具有肯定，谅必的意思。-Linda has gone to work,but her bicycle is still here.-She must have gone by bus.,Grammar,3)ought to have done sth,should have done sth本应该做某事，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。,Grammar,4)neednt have done sth 本没必要做某事I dressed very warmly for the trip,but Ineednt 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.,Grammar,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 needntMust you?/dont have to.典型例题1）-Could I borrow your dictionary?-Yes,of course,you_.A.mightB.will C.can D.should答案C.could表示委婉的语气，并不为时态。答语中of course，表示肯定的语气，允许某人做某事时，用can和 may来表达，不能用could或might。复习：will 与you连用，用来提出要求或下命令。should与you 连用，用来提出劝告,Grammar,2）-Shall I tell John about it?-No,you _.Ive told him already.A.needntB.wouldntC.mustntD.shouldnt 答案A。neednt 不必，不用。wouldnt 将不,不会的。mustnt 禁止、不能。shouldnt不应该。本题为不需要，不必的意思，应用neednt。,Grammar,3）-Dont forget to come to my birthday party tomorrow.-_.A.I dont B.I wont C.I cant D.I havent 答案B.will既可当作情态动词，表请求、建议、也可作为实义动词表意愿、意志、决心，本题表示决心，选B。,Grammar,情态动词,情态动词的应对策略3）考试时，如果有原因说明自己的猜测，一般应该must,cant用而不是may,may not。He cant have stolen the money;he is not such kind of person.Some pleasant thing must have happened to him.He is so excited.,Grammar,情态动词的应对策略其它“情态动词+动词的完成形式”并不表示推测，而分别表示：could have done本来能够 He didnt take part in the competition,he _ though.A.won B.didnt win C.could win D.could have won neednt have done 本来没不要 You _.There was plenty of time.A.neednt hurry B.cant hurry C.mustnt have hurried D.neednt have hurried,情态动词,Grammar,情态动词的应对策略其它“情态动词+动词的完成形式”并不表示推测，而分别表示：should/ought to have done 本来应该 You _ me earlier.I could have helped you.A.should tell me B.should have told C.need to tell D.neednt have told shouldnt/oughtnt to have done 本来不应该 You _ him so closely;you should have kept your distance.A.shouldnt follow B.mustnt follow C.couldnt have been following D.shouldnt have been following,情态动词,Grammar,情态动词的应对策略其它“情态动词+动词的完成形式”并不表示推测，而分别表示：might have done 本来应该（用来表示一种责备）You _ even though you were busy at that time.A.might help him B.must have helped him C.might have helped him D.should help him这类题在设计干扰项时，一般都会有情态动词推测性用法的涉及，应注意分词上下文的逻辑和语意关系。,情态动词,Grammar,1.You _Jim anything about it.It was none of his business.2000a.neednt have told b.neednt tell c.mustnt have told d.mustnt tell 2.He _unwisely,but he was at least trying to do something helpful.1999a.may have acted b.must have acted c.should act d.would act,Grammar,3.Much as_,I couldnt lend him the money because I simply didnt have that much spare cash.1999a.I would have liked to b.I would like to have c.I should have to like d.I should have liked to 4.You _Mark anything.It was none of his business.1998neednt have told b.neednt tell c.mustnt have told d.mustnt tell,Grammar,5.As it turned out to be a small house party,we _so formally.1996need not have dressed up b.must not have dressed upc.did not need to dress up d.must not dress up 6.The meetings been cancelled.Ann _ all that work.1995need to do b.need have c.neednt have done d.needed not to do,Grammar,7.“She must be in the dormitory now.”“No,she _ be there.I saw her in the classroom a minute ago.”1994mustnt b.cant c.couldnt d.wouldnt8.He _ the 8:20 bus because he didnt leave home till 8:25.1994couldnt have caught b.ought to have caught c.shouldnt have caught d.must not have caught,