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1、Grammar,情态动词用法,情态动词的语法特征,1)情态动词不能单独做谓语，后面只能接不带to的不定式（除ought 和have外）。,2)情态动词没有人称,数的变化,但有些情态动词,如can、will也有一般式和过去式的变化。,只作情态动词的 can/could,may/might,ought to,must可情态可实义的 need,dare 可情态可助动词的 shall/should,will/would相当于情态动词的 have to,used to,can的主要用法是：1.表示体力或脑力方面的能力：The girl can dance very well.2.在口语中,can可以表示
2、请求或允许，could可以代替can表示请求,但语气较can客气、委婉:Can I sit here?,can 和could：,3表示推测事物的可能性等:表示“理论上或逻辑上的可能”“有时可能会”Anybody can make mistakes.(只表示理论上的可能性)An accident can happen if you do this.(表示事情肯定会发生),2)could的主要用法是：A.could 是can的过去式,表示与过去 有关的能力和推测:eg.We all knew that the young man couldnt be a doctor.,以could或would提
3、问时，不能再以could或would作答，而应该用can或will。Could I borrow your dictionary?Yes,of course you can.,can表示“能够”时与短语be able to同义，但can只用于一般现在时或过去时，而后者可用于各种时态。,与be able to 的区别：could 只有现在和过去时态，强调能力；be able to有各种时态，表示“一时”的能力,强调结果.“有能力并且做了”,can的特殊句型：can not.too/enough无论怎么.也不过分；越.越好 You cant be too careful.can not but d
4、o sth 不得不，只好 I cant but admire your bravery.,may 和might：may 常用来表示：A.表示请求、允许;比can较为正式，否定回答时，一般要用mustnt，表示“禁止、阻止”had better not“最好别”:eg.May I come in?You may go now.May I watch TV after supper?Yes，you may./No，you mustnt.,eg.-I believe the man is from England.-But I may be wrong.The guest may arrive th
5、is afternoon.在肯定句中，may 的可能性比can 高，may 表示现实的可能性，can 表示理论上的可能性。如：,B.表示说话人的猜测:“也许”“可能”:通常只用于肯定句和否定句中。,The road may be blocked.这条路可能不通了。The road can be blocked.这条路可能会是不通的。在疑问句中，表示可能性用can。如：Where can he be?他会在哪呢？,C.表示祝愿;但语气较正式:eg.May you succeed!May you have a good journey!might 的用法有:多在间接引语中表示过去的可能和允许。如:
6、She said that he might take her bike.她说他可以拿她的自行车去用。,She might go home tomorrow.说不定他明天会回家。表示现在的许可,语气比may 较委婉,一般用于疑问句(包括间接疑问句),不可用于肯定句或者否定句。如:Might I have a word with you?我可以和你说句话吗？,表示现在的可能，其可能性要比 may 小。如：,1.I wish.,may I?2.may/might well do sth 很可能；（完全）能 He may well be proud of his son.3.may/might as
7、 well do sth 不妨.倒不如 You may as well stay here over the night.,will和would：,1.表示主观意志或意愿。will指现在，would指过去 eg.I will never do that again.They said that they would help us.用于否定句，表示“不肯”“不乐意”He wont say words like that.,2.在疑问句中用于第二人称，提出请求或询问。eg:If you want help,let me know,will you?如果你需要帮助,让我知道,好吗?,祈使句反意疑问
8、句,Will you type this,please?请打印这个,好吗？Wont you sit down?请坐下,好吗？3.would比will客气委婉。eg:Would you help us,please?请您帮助我们，好吗？,（表请求）,表示习惯性，经常性，倾向性，译作“总是”“惯于”I will buy some snacks after lunch every day.He would go to his grandpas after school when he was young.,shall和should：,1.用于第一人称，表示征求对方的意见 Shall we go by
9、 train,Mom?妈妈，我们乘火车去好吗？（用于征求对方的意见，情态动词）Shall I close the door?,用于第一、三人称的疑问句，表示说话人征求对方的意见和向对方请示 Shall we begin our lesson?Shall the driver wait？,用于第二、三人称的陈述句，表示说话人给对方的命令、警告、允诺或威胁 You shall go with me.He shall be punished.,用于所有人称，表示规章，法令，语言等“必须”This law shall come into effect on May 1st,2.should表示义务、建
10、议、劝告，意为“应该”。eg:You should keep your promise.你应该遵守诺言。,表示语气“竟然”,He should be such a rude person.,Ought to1.表示“应该”You ought to go to see the doctor.(ought to 的语气比must 弱)You oughtnt(ought not)to smoke so much.Ought you to smoke so much?2.表示“预测”，婉转,比must语气弱 They ought to be there by now.,should 和ought to
11、的区别含义大致相同，ought to 强调在客观上（法律，章程和道义），比should语气强。should强调主观上，表示主语的职责和义务或说话人的劝告。You ought to go and see Mary tomorrow.You shouldnt judge a man always by the clothes.,must和 haveto,1.must用于一般问句中,肯定回答用must否定式用neednt或dont have to，做“不必”,mustnt表示“禁止，不允许”,MustIfinishallassignmentsatatime?,Yes,you must.No,youn
12、eednt.,I dont like this TV set.We must buy a new one.There was no more bus.They had to walk home.,2.表示“必须”这个意思时，must和haveto稍有区别。must着重说明主观看法，haveto强调客观需要。另外，haveto能用于更多时态。,Youmustbethenewteacher.Hemustbejoking.Thereisnobodyhere.Theymusthaveall gonehome.,3.must表示对某人某事的猜测,作“准是”,“一定”,一般用于肯定句中。对过去发生的事情作
13、肯定判断用must have done,He must come and worry her with question,just when she was busy cooking the dinner.Of course，after I gave her my advice，she must go and do the opposite.,4.must表示“偏要,硬要”,指做令人不快的事情,可兼做行为动词的情态动词：need、dare,情态动词(+动词原形),行为动词,.,need,dare,1.无人称和数的变化;,2.尤其用于：,*否定句及疑问句中;,*在if/whether之后;,*或
14、与hardly,never,no one,nobody连用;,3.常以neednt 和darent 的形式出现;,4.dare有其过去时dared.,多用于肯定句;(sb.)need to do dare to do(sth.)need to be done(sth.)need doing,注意对need问句的回答:-Need I finish the work today?-Yes,_.No,_.No,_.,you must,you neednt,you dont have to,neednt 对其它情态动词的回答:-Shall I tell John about it?-No,you _.
15、-Must we do it now?-No,you _.,neednt(dont have to),neednt(dont have to),could,might,would,should都可表示委婉语气。如:I wonder if you could let me use your cell phone.Might I know your telephone number?,委婉语气,.can/could,may/might和must表推测：,1、must：“一定是、准是”只用于肯定，其结构如下：must+动词原形：对一般现在时推测；must+be doing：对现在进行时的推测；mus
16、t+have done：对过去情况的推测；2、can/could：用于否定和疑问，cant/couldnt+动词原形：“不可能”cant/couldnt+be doing：“不可能在做”cant/couldnt+have done：“不可能已经”3、may/might：“也许、可能”用于肯定、否定，may/might+动词原形：may/might+have done：may/might not+动词原形：may/might not+have done：,注意：must/can/may表推测时，其反意疑问句的构成如下：He must be in the classroom,isnt he?He
17、must have seen the film,hasnt he?He must have seen the film last month,didnt he?,、情态动词表虚拟时的结构情态动词后接完成体的四个句型：、could/might have done：“本来可以”、should/ought to have done：“本应该”、should not/ought not to have done：“本不该”、need+have+done 本来需要做某事而没有做。neednt have done：“本不必”、would+have+done“本来会做”注意：以上五个结构都指过去的情况,表并
18、未如此.,2.含if条件句的复合句中：句型一：If（过去式/were），主句(should/would/could/might+动原)“愿意、会/能/也许”句型二：If（had done），主句(should/would/could/might+have done)“愿意、会/能/也许”,can/could,may/might,should和must都可表示肯定的推测。can/could表示客观可能性；may表示推测时，其语气不肯定；might语气更弱，表示某事实际发生的可能性；should表示确定或可能有的未来或期待；must表示肯定的语气。如：,推测的可能性,I think Ill giv
19、e Bob a ring later in the week.You _.You havent been in touch with him for ages.A.will B.may C.have to D.should,D,练习坊,I.Choose the correct answer.,2.John,look at the time._ you play the piano at such a late hour?A.Must B.Can C.May D.Should,A,3.There _ any difficulty about passing the road test since
20、 you have practiced a lot in the driving school.A.mustnt be B.shant have C.shouldnt be D.neednt have,C,4.The World Wide Web is sometimes jokingly called the World Wide Wait because it _ be very slow.A.Should B.must C.will D.can5.Helen _ go on the trip with us,but she isnt quite sure yet.A.shall B.mu
21、st C.may D.can,D,C,6.Someone is knocking at the door._ it be Venis?No,it _ be her;she left for New York this morning.A.Can;mustnt B.Might;cant C.May;doesnt D.Can;cant,D,7.Mike promised his doctor he _ not drink,and he has never drunk ever since.A.might B.should C.could D.would,D,8.Is there a movie o
22、n in the cinema tonight?There _ be.I will phone the cinema and find it out.A.might B.should C.can D.must,A,9.When I was studying at Beijing University,I _ take a walk along the lake every evening.A.will B.would C.could D.shall,B,10.Mr Brown,many students want to see you._ they wait here or outside?A
23、.Shall B.Will C.Can D.Would,A,may;mightI asked if I _ go home half an hour earlier today.There _ not be enough money to pay for the repairs.,might,may/might,对过去的猜测,must have done could/can have done should have done would have done need have done,cant have done,couldnt/cant have done,shouldnt have d
24、one,wouldnt have done,neednt have done,一定做了某事,肯定没做某事,可能做了某事,本该做某事,本来是要做某事的,本需要做某事,1.With so much work on hand,you _ to see the game last night.A.mustnt go B.could have goneC.shouldnt go D.shouldnt have gone,2.-There were already five people in the car but they managed to take me as well.-It _a comfo
25、rtable journey.()A.cant be B.mustnt have been C.shouldnt be D.couldnt have been,D,D,3.where is my dictionary?I remember I Put it here yesterday.-You_ it in the wrong place.must put B.should have putC.might put D.might have put4.The weather turned out to be fine Yesterday.I _ the trouble to carry my
26、umbrella with me.A.should have taken B.could have takenC.neednt have taken D.mustnt have taken,D,C,3.The room is in a terrible mess;it _ cleaned.A.cant have been B.couldnt be C.may have been D.would be,A,-_ I go out to play,mum?-No,you_.You should do your homework first.A.Might;wouldnt B.May;had bet
27、ter not C.Must;mustnt D.Need;mustnt,B,练习坊,I.Choose the correct answer.,2.-Where is Emma?-I cant say for sure where she is,but she_ be out shopping.A.can B.should C.must D.may,D,3.The room is in a terrible mess;it _ cleaned.A.cant have been B.couldnt be C.may have been D.would be,A,4.How _ you say th
28、at you really understand the whole story if you have covered only part of the article?A.can B.must C.need D.may,A,5.There _ be any difficulty about passing the road test since you have practised a lot in the driving school.A.mustnt B.shant C.shouldnt D.neednt,C,6.-There were already five people in t
29、he car but they managed to take me as well.-It _a comfortable journey.()A.cant be B.mustnt have been C.shouldnt be D.couldnt have been,D,7.The fire spread through the hotel very quickly but everyone _ get out.()A.had to B.would C.could D.was able to,D,8.Peter _ come with us tonight,but he isnt very
30、sure.must B.can C.may D.will,C,9.-Could I call you by your first name?-Yes,you_.A.will B.could C.may D.might,C,10.Sorry,I m late.I _ have turned off the alarm clock and gone back to sleep again.might B.should C.can D.will,A,11.-Excuse me,but I want to use your computer to type a report.-You _ have m
31、y computer if you dont take care of it.shant B.might not C.neednt D.shouldnt,A,12.-When can I come for the photos?I need them tomorrow afternoon.-They _be ready by 12:00.A.can B.should C.might D.need,B,13.With so much work on hand,you _ to see the game last night.A.mustnt go B.could have goneC.shoul
32、dnt go D.shouldnt have gone,D,14.Johnny,you _ play with the knife,you _ hurt yourself.A.wont;cant B.mustnt;mayC.shouldnt;must D.cant;wouldnt,B,15.There is no light in the dormitory.They must have gone to the lecture,_?A.didnt they B.dont they C.mustnt they D.havent they,D,16.I missed the bus,so I _
33、go home on foot.A.must B.may C.can D.had to,D,2.A:_ Xiao Feng find the origin of Easter from that book?B:No,he _.,1.A:_ you like to go to a special event with us on Saturday?B:Yes,I _ _.,Would,d like to go with you on,Saturday,Could,couldnt find it,Exercise,3.A:_ I go with my friend to the harvest f
34、estival?B:Yes,you _ _.,4.A:If I want to be a doctor _ I study science?B:Yes,you _.,should study science,May,may go(with your,should,friends),5.A:He is very handsome._ he play the role of the prince?B:No,he _ _.,cant play the role of the,Can,prince,6.A:The neighbour s children are older this year._ t
35、hey stop playing tricks at Halloween?B:Perhaps,they _ _._ _.,Might,or Should,might stop,or should stop playing tricks,playing tricks at Halloween,at Halloween,can;couldWhen I was young I _ climb any tree in the forest.Learning a language _ be a real challenge.,could,can,II.选用正确的情态动词填空。,will;wouldWhe
36、n he got older,he _ never do his homework.Nancy _ keep talking unless you tell her to shut up.,would,will,shall;shouldBy now,they _ already be in Dubai.I _ be replaced by someone from the New York office.,should,shall,must;cantYou _ have stayed up.You look so tired.You _ be 45!I thought you were abo
37、ut 25 years old.,must,cant,Harvest and Thanksgiving festivals canbe very happy events.(P2)考点 情态动词can的用法。考例1 It is usually warm in my hometown in March,but it _ be rather cold sometimes.(福建 2008)A.must B.can C.should D.would,考点点拨 考例回顾,选B。can表示“可能”，意为“有时天气可能会相当冷”。must必须、肯定；should应该；would表示过去常常。,考例2 You _ be hungry already you had lunch only two hours ago!(浙江 2008)wouldnt B.cant C.mustnt D.neednt选B。此题考查情态动词表推测。cant意为“不可能”；mustnt意为“禁止、一定不要”；wouldnt常表示对现在或将来情况的虚拟；neednt意为“没有必要”。,
