八年级情态动词

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,情态动词,现在式,过去式,否定式,一般,情态,动词,can,could,cannot / cant; couldnt,may,might,must not / mustnt,may not; might not,cannot / cant; couldnt,must,must,need not / neednt,must not / mustnt,shall,should,shall not / shant; shouldnt,will,would,will not / wont; wouldnt,need,/,need not / neednt,短语,情态,动词,be able to,was / were able to,be not able to,have / has to,had to,dont/doesnt have to; didnt have to,used to,used not to / didnt use to,ought to,/,ought not to / oughtnt to,exercise,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。,备注：,情态动词无人称和数的变化；不能单独,使,用，必须与其后的动词原形构成谓语,一、,can, could,1),表示能力（体力、知识、技能）,Can you lift this heavy box?,（体力）,Mary can speak three languages.,（知识）,Can you skate?,（技能）,此时可用,be able to,代替。,Can,只有一般现在时和一般过去式；而,be able to,则,有,更多的时态。,Ill not be able to come this afternoon.,=I cant come this,afternoon.,当表示“经过努力才得以做成功某事”时应用,be able to,，不能用,Can,。如：,He was able to go to the party yesterday evening in spite of the heavy rain.,2),表示请求和允许。,-Can I go now?,- Yes, you can. / No, you cant.,此时可与,may,互换。在疑问句中还可用,could, might,代替，,不是过去式,，只是语气更委婉，不能用于肯定句和答语中。,- Could I come to see you tomorrow?,- Yes, you can. ( No, Im afraid not. ),3),表示客观可能性（客观原因形成的能力）。,There is still a lot of time, so we can go by bus.,This hall can hold 500 people at least.,4),表示推测（惊讶、怀疑、不相信的态度），用于疑问句、否定句和感叹句中。,Can this be true?,This cant be done by him.,How can this be true?,二、,may, might,1),表示请求和允许。,might,比,may,语气更委婉，而不是过去式。否定回答时可,cant,或,mustnt,，表示“不可以，禁止”。,Might/ May I smoke in this room?,No, you mustnt.,May/Might I take this book out of the room?,Yes, you can. (No, you cant / mustnt. ),用,May I.,？征徇对方许可时比较正式和客气，而用,Can I.,？在口语中更常见。,2,）用于祈使句，表示祝愿。,May you succeed!,3,）,表示推测、可能性（不用于疑问句）。,might,不是过去式，它所表示的可能性比,may,小。,1,He may /might be very busy now.,2,Your mother may /might not know the truth.,三、,must, have to,1),表示必须、必要。,You must come in time.,在回答引出的问句时，如果是否定的，不能用,mustnt,（禁止，不准），而用,neednt,dont have to,（不必）,.,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,have to,则强调客观需要。,Must,只有一般现在时，,have to,有更多的时态形式。,1,he play isnt interesting, I really must go,n,ow.,2,I had to w,o,rk when I was your age.,3),表示推测、可能性（只用于肯定的陈述句）,1,Youre Toms good friend, so you must know what he likes best.,2,Your mother must be waiting for you now.,四、兼做情态动词和实意动词的,need,(1),在疑问句和否定句中可作情态动词或实意动词,Need you do so? / Do you need to do so?,You neednt do so. / You dont need to do so.,(2),在肯定句中只能作实意动词,You need to do so. He needs to do so.,(3) need,作情态动词,+,动词原形,作实意动词,+,to+v,. / + n. / +,ving,The little girl needs some help.,The old lady needs to look after the baby.,The old lady needs looking after well. = The old lady needs to be looked after well.,练习：,1._IwaterthetreesonTuesday?, No,youneednt.,A.CanB.MustC.MayD.Shall,2. _ you come to my party? Certainly! Id love to,。,A. Must B. Should C. Can D. Might,3. Will you answer the phone? It _ be your mother.,Sorry, I _. Im busy.,A. can, mustnt B. will, cant C. may, cant D. need, will,4. May I smoke here?, No, you _ only do that in the smoking room.,A. can B. need C. mustnt D. couldnt,5. Will you come to my party?,Sorry, But I _ look after my little brother.,A. need B. have to C. can D. could,B,C,C,