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1、1,Model Verb,2,定义,情态动词是一种本身有一定的词义,但要与动词原形及其被动语态一起使用，给谓语动词增添情态色彩，表示说话人对有关行为或事物的态度和看法，认为其可能、应该或必要等。,情态动词后面加动词原形。,注意,3,分类：,情态动词有四类：,只做情态动词：must, can(could), may(might), ought to,可做情态动词又可做实义动词：need, dare,可做情态动词又可做助动词：shall (should), will (would),具有情态动词特征：have (had, has) to, used to,4,位置:,情态动词在句中放在谓语动词之前
2、, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前。,I can see you. Come here. 我能看见你，过来吧。 He must have been away. 他一定走了。 What can I do for you? 我能帮你吗？ How dare you treat us like that！ 你怎能那样对待我们！,5,特点:,情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 “not“。 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在或将来。情态动
3、词属非及物动词，故没有被动语态。,He could be here soon. 他很快就来。 We cant carry the heavy box. 我们搬不动那箱子。 Im sorry I cant help you. 对不起，我帮不上你。,6,The basic uses of Modal Verbs,7,一、 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。（考点一）
4、：Can只有一般现在时和一般过去；而be able to则有更多的时态。Ill not be able to come this afternoon.,当表示（考点二）“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.,8,一、 can, could,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, m
5、ight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. ) (考点),9,一、 can, could,3) 表示客观可能性（客观原因形成的能力）。,Theyve changed the timetable, so we can go by bus instead. 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 b
6、e true? This cant be done by him. 对比：This must be done by him. How can this be true?,10,1. Can,Could 过去式；语气更委婉,Can 表示习惯能力，而be able to表示经过那里而做成了某事。 2. 在否定结构中，二者可以互换。,1.在否定、疑问句中表示“对过去发生行为的可能性猜测。 2. 在肯定句中表示“本来可以做而未做”,The door was lacked. She couldnt have been at home.（推测：） You could have been more care
7、ful.（但实事上没有更细致）,11,二、 may, might,1) 表示请求和允许。might比 may语气更委婉，而不是过去式。否定回答时可用（考点一）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。,12,二、 may, might
8、,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。 1He may /might be very busy now. 2Your mother may /might not know the truth.,13,1. May,Might 过去式；语气更委婉,1.在否定、肯定句中表示对过去动作的推测 “也许是” 2. Might+have+p.p表示虚拟，表“劝告、责备之意。”,Eg. 1. She may be still waiting for us. 2. May I come in?
9、 3.May you have a happy holiday.,Eg. 1. He might have spoken to her yesterday.（委婉推测） 2. You might have told me earlier.（你或许可以早点告诉我，但实事上没有，有责备之意）,14,三、 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，(考点一)不能用mustnt（禁止，不准），而用neednt, dont have to（不必）.,- Must we hand in our exercise bo
10、oks today? - Yes, you must. - No, you dont have to / you neednt.,15,三、 must, have to,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。,He play isnt interesting, I really must go now. I had to work when I was your age.,3) 表示推测、可能性（只用于肯定的陈述句）,Youre Toms good friend, so you must know wha
11、t he likes best. Your mother must be waiting for you now.,16,1. Must,表示肯定的猜测,但只用于肯定句， 而mustnt 表示“禁止、不准”,Must表示主观 Have to表示客观需求 Have got to 多见于口语,3. must + have +p.p,对过去事情的肯定猜测。,Eg. The road is wet. It must have rained last night.,17,四、 shall, should,1) shall 用于第一人称，征求对方的意见。,What shall we do this eve
12、ning? Shall we go there by bus?,2) shall 用于 (考点一) 第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。 1. You shall fail if you dont work hard.(警告) 2. He shall have me the book when I finish it.(允诺) 3. He shall be punished.(威胁),18,1、Shall /should,shall/should + have +p.p ought to,表示本应该做而未做。,should 过去式 语气更委婉,Eg. You should
13、have been five minutes ago.,2、,2、,19,五、 will, would,1) 表示请求、建议等，would更委婉,Will / Would you pass me the ball, please?,2) 表示意志、愿望和决心。 1. I will never do that again. 2. They asked him if he would go abroad.,20,五、 will, would,3) would表示过去反复发生的动作或某种倾向。would表示过去习惯时比used to正式，且没有 (考点) “现已无此习惯”的含义。,1. During
14、 the vacation, he would visit me every other day. 2. The wound would not heal治愈 . 创伤难以愈合 Would 后只能接表示动作的动词。used to 则还可以接表示状态的动词。（考点）He used to be a worker.,4) 表示估计和猜想。 It would be about ten oclock when she left home.,21,Will/ would,1、Would 后只能接表示动作的动词。,2、used to 则还可以接表示状态的动词。 Eg. He used to be a wor
15、ker.,22,used to和would的区别,1. 都可以表示过去重复的习惯，used to 含有“过去怎样而现在却不这样了”的意思；而would则单纯表示过去的习惯性动作，常和often, everyday等连用。,He would take a walk near the forest in the evening. （现在可能散步也可能不散步了）,He used to take a walk near the forest in the evening. （而现在不散步了）,23,1. She isnt what she used to be. 她跟过去不一样了。 （表示对比，不可用
16、would）,2. There used to be a park. 以前这里有一个公园。 表示过去的状态，只能用used to，不可用would。,2.不能用would的情况,24,六、 dare, need,1) dare作情态动词用时, 常用于疑问句、否定句和条件从句中, 过去式形式为dared。,How dare you say Im unfair? He darent speak English before such a crowd, dare he? If we dared not go there that day， we couldnt get the beautiful flowers.,2) need 作情态动词用时, 常用于疑问句、否定句。在肯定句中一般用must, have to, ought to, should代替。,1You neednt come so early. 2. - Need I finish the work today? - Yes, you must. / No, you neednt.,
