助动词与情态动词-常晶.ppt

助动词与情态动词讲解,常晶,助动词的形式及用法,助动词有be, have, do, will, shall。它们本身没有词义，只和实义动词的一定形式构成复合谓语，用来表示时态和语态，构成否定、疑问及加强语气等。,1、be (am, is, are, were, been),(l)“be + -ing”构成进行时态； (2)“be + 过去分词”构成被动语态； (3)“be + 动词不定式”构成复合谓语： 表示按计划安排要发生的事。 The prime minister is to visit Japan next year. 总理将于明年访问日本。 用于命令。 Youre to do your homework before you watch TV.你得做完了作业才能看电视。,2、have (has, had),(1)“have/has+过去分词”构成完成时态. Eg: Have you seen the film ? (2)“have/has been + -ing”构成完成进行时态。 Eg：What have you been doing these days? 这些日子你一直在干什么?,3、do (does, did),(1)“do not + 动词原形”构成行为动词的否定式。 Eg:His brother doesnt like playing basket. (2)“Do + 主语 + 动词原形”构成行为动词的一般疑问句。 Eg:Does he go to school by bike every day? (3)“do + 动词原形”用于祈使句或陈述句中表示加强语气。 Eg:I did go to see him, but he wasnt at home. 我确实去看望他了，但他不在家。 Do do some work. 请一定做点什么； (4)代替前面刚出现的动词以避免重复。 My mother told me to go to bed early. So I did.,4.will, shall (would, should),will 、shall+动词原形”构成一般将来时，一般来说shall用于第一人称，will用于第二人称或第三人称，口语中常用will代替shall， Eg：We will have a meeting to discuss the problem.,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。,语法特征,1. 情态动词没有人称和数的变化,即情态动词第三人称单数不加- s (have to, have got to, be able to 除外)。,2. 情态动词本身具有一定词义, 但意思不够完整, 不能单独做谓语, 后接动词原形一起构成谓语部分 。 3. 情态动词无非谓语形式,即无不定式、分词(现在分词，过去分词）等形式。,Sum up,1. can和be able to 1) can (could) 表示能力、可能, 只用于现在式和过去式 2) be able to可以用于各种时态。,只用be able to的情况： a. 位于助动词后。Has/have been able to b. 情态动词后。 We must/may be able to show how science is beneficial to our society。 c. 用于句首表示条件。 Being able to get the tickets for that Hockey game, I am very excited now. 能买到那个冰球比赛的票，我现在非常激动。 d. 表示成功地做了某事时,只能用was/ were able to,不能用could。,注意:could还可不表示时态,只表示 1) 提出委婉的请求,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.,2. may和might,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。 e.g. May God bless you! He might be at home. 注: 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。 e.g. If that is the case, we may as well try.,3. have to和must,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, 即主观上的必要。 e.g. My brother was very ill, so I had to call the doctor in the middle of the night. He said that they must work hard.,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。 e.g. He had to look after his sister yesterday.,3) 在否定结构中：dont have to 表示“不必”; mustnt表示”禁止”。 e.g. You dont have to tell him about it. 你不必把这事告诉他。 You mustnt tell him about it. 你不能把这事告诉他。,4. must表示推测 1) must用在肯定句中表示较有把握的推测,意为“一定”。 2) must表对现在的状态或现在正发生的事情的推测时, 后面通常接系动词be的原形或行为动词的进行时。,e.g. You have worked hard all day. You must be tired.（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. 他现在肯定呆在那儿。 He must stay there. 他必须呆在那儿。,3) must 表示对已发生的事情的推测时, 要接完成时。 e.g. I didnt hear the phone. I must have been asleep. 4) must表示对过去某时正发生的事情的推测, 后面要接完成进行时。,e.g. -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. e.g. If Tom didnt leave here until five oclock, he cant be home yet.,5.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。 e.g. I dont know where she is. She may be in Wuhan.,2) 情态动词+动词进行时, 表示对现在或将来正在进行的情况进行推测。 e.g. At this moment, our teacher must be correcting our exam papers.,3) 情态动词+动词完成时, 表示对过去情况的推测。 e.g. The road is wet. It must have rained last night. 4) 情态动词+动词的完成进行时, 表示对过去正在发生事情的推测。 e.g. Your mother must have been looking for you.,5) 推测的否定形式,疑问形式用cant, couldnt表示。 e.g. Mike cant have found his car, for he came to work by bus this morning. 注: could, might表示推测时不表示时态,其推测的肯定程度不如can, may。,6.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。 e.g. 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., 表示对过去时间里可能发生的事情的推测,语气较强,具有“肯定”的意思。 e.g. - Linda has gone to work, but her bicycle is still here. - She must have gone by bus.,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”。 e.g. 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。) 注: ought to 在语气上比should 要强。,4) neednt have done sth. 本没必要做某事 e.g. I dressed very warmly for the trip, but I neednt have done so. The weather was hot. 5) would like to have done sth. 本打算做某事 e.g. I would like to have read the article, but I was very busy then.,7. should和ought to,should 和ought to 都为“应该”的意思,可用于各种人称。 e.g. - 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。,8. 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 (not) do sth.,e.g. It 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“(过去)本来最好”。 e.g. You had better have come earlier.,9. would rather表示“宁愿” would rather (not) do would ratherthan宁愿而不愿 e.g. If I have a choice, I would rather stay at home than go out with you！,10. will和would 1) would like to do = want to 想要 e.g. 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。 e.g. 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。 e.g. Wont you sit down?,11. need和dare 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,两者都常用于疑问句,否定句和条件句。并注意回答用need 提问的句子时，肯定回答用must。 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+ n. / to do sth. 2) 情态动词: need,只用原形need后加do,否定形式为need not. e.g. - Need you go yet? - Yes, I must. / No, I neednt. 3) need, want, require, worth(形容词)后面接doing也可以表示被动。 need doing = need to be done,