1、有一定的词义，但词意不完整有一定的词义，但词意不完整,不能单独作谓语，必须和实义不能单独作谓语，必须和实义动词连用动词连用,表示说话人对某一动表示说话人对某一动作或状态的态度和看法。情态作或状态的态度和看法。情态动词后面跟动词原形，没有人动词后面跟动词原形，没有人称和数的变化。称和数的变化。Can you lift this heavy box?(体力体力)Mary can speak three languages.(知识知识)Can you skate?(技能技能)此时可用此时可用be able to代替。代替。can只有一般只有一般现在时和一般过去时；而现在时和一般过去时；而be abl
2、e to则有更多的时态。则有更多的时态。例如：例如：Ill not be able to come this afternoon.(一般将来时一般将来时)如：如：He was able to go to the party yesterday evening in spite of the heavy rain.-Can I go now?-Yes,you can./No,you cant.-Could I come to see you tomorrow?-Yes,you can.(No,Im afraid not.)Theyve changed the timetable,so we ca
3、n go by bus instead.This hall can hold 500 people at least.Can this be true?This cant be done by him.How can this be true?1)表示请求和允许。表示请求和允许。might比比 may语语 气更委婉，而不是过去式。否定回气更委婉，而不是过去式。否定回答时可用答时可用cant 或或mustnt，表示，表示“不不可以，禁止可以，禁止”。例如：例如：-Might/May I smoke in this room?-No,you mustnt.-May/Might I take thi
4、s book out of the room?-Yes,you can.(No,you cant/mustnt.)用用May I.？征徇对方许可时比较正式？征徇对方许可时比较正式和客气，而用和客气，而用Can I.？在口语中更常见。？在口语中更常见。2)用于祈使句，表示祝愿。用于祈使句，表示祝愿。例如：例如：May you succeed!3)表示推测、可能性表示推测、可能性(不用于疑问不用于疑问 句句)。might不是过去式，它所表示不是过去式，它所表示 的可能性比的可能性比may小。小。例如：例如：He may/might be very busy now.Your mother may/
5、might not know the truth.1)表示必须、必要。表示必须、必要。例如：例如：You must come in time.-Must we hand in our exercise books today?-Yes,you must.-No,you dont have to/you neednt.2)must是说话人的主观看法，而是说话人的主观看法，而have to 则强调客观需要。则强调客观需要。must只有一般现在只有一般现在 时，时，have to 有更多的时态形式。有更多的时态形式。例如：例如：His play isnt interesting,I really m
6、ust go now.I had to work when I was your age.3)表示推测、可能性表示推测、可能性(只用于肯定的陈只用于肯定的陈 述句述句)例如：例如：Youre Toms good friend,so you must know what he likes best.Your mother must be waiting for you now.用用must,have to填空。填空。1.I know I _ study hard.2.My mother is ill.I _ look after her at home.musthave to1)Please a
7、sk that man.He _ know that.2)The light is on,so he _ be at home.3)It _ be Wei Fang.She is at school now.4)Are you coming to Jeffs party?Im not sure.I _ go to the concert instead.maymustcantmightcan,may/might,must 表推测表推测4.shall和和should征求对方意见征求对方意见 Shall we go out for a walk?What shall we drink?1)shal
8、l2)should We should protect our environment.You should do it better next time.劝告义务责任劝告义务责任 用用shall/should填空。填空。1.When _ we meet?2.You _ see a doctor.shallshould5.will,would 例如例如:Will/Would you pass me the ball,please?例如例如:I will never do that again.They asked him if he would go abroad.During the vac
9、ation,he would visit me every other day.The wound would not heal.It would be about ten oclock when she left home.I should help her because she is in trouble.You ought to take care of the baby.6.should,ought to You should/ought to go to class right away.Should I open the window?He must be home by now
10、.(断定他已到家断定他已到家)He ought to/should be home by now.(不太肯定不太肯定)This is where the oil must be.(直爽直爽)This is where the oil ought to/should be.(含蓄含蓄)1.你必须马上回家。你必须马上回家。2.他一定吃过什么东西了。他一定吃过什么东西了。3.吃饭之前不能吃零食。吃饭之前不能吃零食。You must go home now.He must have eaten something.You mustnt eat snacks before meals.4.我可以问你的名
11、字吗？我可以问你的名字吗？5.你能用英语说吗？你能用英语说吗？6.我们应该准时去上学。我们应该准时去上学。7.你没有必要那么做。你没有必要那么做。May I ask your name?Can you speak in English?We should go to school on time.You neednt do that.1.-Dad,must I finish my homework today？-No,you _.You may finish it tomorrow.(2008朝阳朝阳)A.neednt B.mustnt C.dont D.wont2.-May I put my
12、 bike here?(2008广安广安)-No,you _.You should put it over there.A.may not B.mustnt C.neednt掌握情态动词问句的回答：掌握情态动词问句的回答：May I?Yes,may.No,mustnt/cant.Must I?Yes,must.No,neednt/dont have to.1.-Is Mr.Brown driving here?(2008安徽安徽)-Im not sure.He _ come by train.A.may B.can C.need D.must2.-Whos that boy reading i
13、n the garden?Is it David?(2008重庆重庆)-It _be David.I saw him in the classroom just now.A.must B.cant C.may D.neednt3.Im sure this book _ Li Leis,because there is his name on it.(2008吉林吉林)A.cant be B.may be C.might be D.must be掌握推测用法掌握推测用法:肯定可能性由肯定可能性由must may might逐步递减逐步递减;cant则用于则用于否定否定句、句、疑问疑问句。句。1.
14、-Lisa,_ you speak French?(2008南京南京)-Yes,but only a little.A.may B.can C.need D.must2.-_ I use your mobile phone?(2008北京北京)-Certainly.Here you are.A.May B.Must C.should D.need3.-Mum,can I go to the movies today?(2008长沙长沙)-No,but you _ finish your schoolwork first.A.can B.cant C.must D.neednt掌握基本用法掌握基
15、本用法:can表能力表能力,may表许表许可可,must表义务。表义务。1.-Is Lucy knocking at the door?(2008长长沙沙)-No.It _be Lucy.She is in Japan.A.neednt B.must C.cant2.-Have you seen my glasses?I _find them.-Sorry,I havent seen them.(2008武汉武汉)A.cant B.shouldnt C.wont D.mustnt3.When traffic lights are red,we _ stop and wait.(2007南京南京
16、)A.may B.can C.must D.might4.-Must I wait for here now?(2006沈阳沈阳)-No,you_.You may give it to me tomorrow.A.dont have to B.mustnt C.cant D.shouldnt1.Where is your mother,Tony?She _ be in the kitchen.I am not sure.2.John,you _ play with the knife,or you _ hurt yourself.maymustntmay/might3.You _ stop your car when the traffic light is red.4.He says that he _ speak at least two foreign languages.5.I will do whatever I _ do to help you.6.Lets go for a picnic this afternoon.Sorry,I _.I have to go to see my grandparents with my father.cantmustcancan
