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1、 GrammarGrammar 情态动的用法情态动的用法Unit 13命题热题热 点： 情态动词态动词 的基本用法; 情态动词态动词 表示态态度的用法; 情态动词态动词 表示推测测的用法; 情态动词态动词 在虚拟语拟语 气中的运用。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.3.情态动词本身具有一定词义,但不能单独做谓语, 后一般 接动词原形一起构成谓语部分 (ought to, have to/have g
2、ot to, be able to除外).4.情态动词无非谓语形式,即无不定式(to do),分词等形 式.SummaryModal VerbsModel VerbsExamplesAbilityNecessityPermissionGuessing (possibility /certainty) Suggestion /AdviceRequestcan / could can / could be able tobe able toHe can/could fly a plane.He can/could fly a plane.must/ have to must/ have to /h
3、ave got to/need/have got to/needHe had to get special He had to get special training. training. can/could can/could may/might/may/might/mustnmustnt tWe must protect water.We must protect water.might/may/could might/may/could /should/must /should/must /will/can/will/canLack of water in the future may
4、 Lack of water in the future may result in several problemsresult in several problems. . could/may / might could/may / might shall/should/ought shall/should/ought to/ had betterto/ had better Could you help me? Could you help me? /Would you like to help /Would you like to help me?me?We had better us
5、e water for We had better use water for more than one purpose.more than one purpose. can/could/willcan/could/will /would/wouldwould/would likePeople can walk this way.People can walk this way. A driver A driver mustnmustnt drive beyond t drive beyond the speed limit.the speed limit.1.can，could 的用法 1
6、）表能力，有“能”、“会”、“能够”的意思Can you drive a car? 你会开车吗？-Yes, I can. -No, I cant. 2）征求许可，意为“可以” Can I use your bike? 我可以?(=may但没 有may 正式）3）表示可能性，常用于否定句和疑问句, 用于 肯定句表示“有时会” 。 Can it be true? 那会是真的吗?Today is Sunday. He cant be at school. Certain things in the home can be dangerous, especially if you have young
7、 children. 4).用于否定句，疑问句和感叹句中表 示怀疑，猜测和惊讶。How can/could you be here?She couldnt/cant be so stupid to do that. 注：过去式could语气比can更加委婉Could I use your car?Of course, I can. (回答允许一般用can) I wonder if you could do me a favor.can 只有一般现在时和一般过去时两种时 态(could)，其他时态要用be able to的形式例如：can 和 be able to 的比较I havent bee
8、n able to get in touch with her. 我一直没能和她联系上。 Her baby will be able to walk in a few weeks.通常can 和 be able to 可以互换 When he was three, he could/was able to swim.如果谈论过去某个时间有能力且做到了某事 ， 用was/were able to而不是could Tom has started an exercise program. He was able to run two miles yesterday without stopping.
9、在否定句中，could与was/were able to 没有区别Tom couldnt run (wasnt able to run) five miles yesterday.2.may，might的用法2.1) 表示许可或征求对方的许可， 有“可以”的意思。例如：You may go now. 你可以走了。May I use your computer? 我用 一下你的电脑可以吗？ 注：过去式might表示的语气更加委婉、客气例如： Might I use your pen for a while?我能用你的钢笔吗 注：回答以may开头的疑问句有如下表达法：例如：- May I smok
10、e here? 我可以在这儿抽烟吗？肯定 Sure/Certainly.-Yes, you may -Yes, please 否定；-No, you cant-No, you mustnt. -No, youd better not.- Please dont.2. 2) 表示猜测，通常只用于陈述句例如：You may be right. 你可能是对的 。It may rain tomorrow. 2. 3) Wish e.g. May all your dreams come true in the future!May you have an everlasting marriage!Ma
11、y you return in safety.2.4)在口语中can可以代替may表示许可 ，但can较随便，may更正式例如：Can I use your bike, John? 约翰， 我可以用一下你的自行车吗？ May I have a look at your license please, sir? 先生，我可以看一下你 的执照吗 3.must 的用法 3.1)表义务，“必须”例如： You must talk to them about their study. 你必须同他们谈谈关于他们学习的事。 3.2) 在否定结构中表不许、禁止例如：You mustnt smoke here.
12、 你不能在这抽烟 。 附：关于must的回答。 例如： Must I clean the dining room at once? 肯定： -Yes, you must. （是的，你必须) 否定： -No, you neednt. （不，你不必) -No, you dont have to.3.3) 表坚定的建议例如：You must come and see us as soon as you get to Shanghai. 一到上海你就得马上来见我们。 3.4) 表推测，暗含有很大的可能性例如：He must be ill. He looks so pale. 他肯定是病了。他的脸色那么
13、苍白。注意may 暗含的可能性较小，must 暗含的可能 性较大。 3.5)还可以表示必然的结果All men must die.4.have to的用法have to 意为为“不得不”，它虽虽属于情态动词态动词， 但它有人称、数的变变化，其疑问问句，否定句的 构成也和其他的动词动词有所不同。Have to 的疑问句和否定句，多用助动词 do构成。例如： Did he have to do it? 他得做那件事吗 He didnt have to do it. 他不需要做那 件事。 4.1 have to the train doesnt start till 7:30.6 Dare 形式和用
14、法:dare同 need一样,既可用作情态动词又可用作实义动词.用作情 态动词时,它只有一种形式,后接动词原形,主要用于疑问句和否定 句.用作实义动词时,它有动词的全部形式,即现在时单数第三人称 dares,现在分词daring以及过去式和过去分词dared,后接带 to 的动词不定式,可用于一切句式. 情态动词Dare 的基本用法: 1.表示敢于,指现在或过去.如: I dare not go there. Dare you ask him? I dont know whether he dare try. The king was so hot-tempered that no one d
15、are tell him the bad news.(指过去是形式不变)dare do, dare not dodared to do, didnt dare (to) doDare he do? e.g. How dare you speak against the boss in public?用于固定习语I dare say/I daresay 我想; 也许My son is not in town, but I dare say he will be before long.我儿子现在不在城里,不过我想不久他会回来的.7.will和would的用法will （1）表示“意愿”，I will help you.(2) 用于第二人称表征求意见，Will you have some more wine?（3）用于第三人称表推测 “想必是”“一定会”。-Somebody is coming upstairs.- Tha
