高中英语语法之情态动词.doc

高中英语语法之情态动词（一）情态动词的定义：情态动词表示说话人对某一动作或状态的态度。（二）情态动词的特点：1）有一定词义；2）不受主语人称和数的变化影响；3）与主要动词的原形（或称不带to的不定式）一起构成谓语（除oughtto作固定词组看待）。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。情态动词属非及物动词，故没有被动语态。will(would), shall(should), can(could), may(might), must, need, dare, ought to, used to, had bette可以与have和be基本助动词连用。不少场合，情态助动词的现在时和过去时形式都可以表示现在、过去或将来时间（三）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 情态动词表猜测A: can / could = be able to 1 表示能力两种时态can (could)，其他时态要用be able to的形式He can speak French.Was/were able to 可以表示成功做成某事的含义* managed to do / succeeded in doing With our help, he was able to build the house. 2 表示请求或许可 Could 比 Can 更加客气* mayCan I go now? Yes, you can.3 表示推测或可能性，常用于否定句和疑问句Can he be at school?Today is Sunday. He cant be at school.Cant couldnt/ Can ? Could? have done There is no light in the room. Can she have gone to bed?She cant have gone to school- its Sunday.Could have done 可用在肯定句中表示过去存在的可能性* may have doneShe could have gone out with some friends yesterday.Could have done 可以表示虚拟语气某事可能发生（并没有发生）It was silly to throw the TV out of the window. It could have hit somebody.批评某人没有完成某事(本可以做某事)You are late again. You could have got up earlier.4 can 表示客观上的可能性*Anybody can make mistakes.B: may and might 1 表示请求和允许 类似用法can could(更加口语化)May I watch TV now? Yes, you may.2 表示可能性; 猜测might比may更加不确定may/might have done 对过去的揣测*He may be busy these days.May not 可能不；不可能；一定不可3 表示祝愿 Wish you success!May you succeed!*C: must and have to1 表示必须；一定要 可以用 have to 代替 must 现在；将来的必须 而且是主观看法*have to 有多种时态 而且强调客观情况I really must stop smoking now.I had to leave early because I wasnt feeling well.Must I come here?Yes, you must. No, you neednt. neednt / dont have to must not 一定不能做某事 mustnt2 must 表示推测 意思非常肯定 “一定是”“一定会”It must be raining outside.Must have done 对过去/完成的推测* must have done, didnt / hasntMust be doing 推测现在正在进行He must have gone over the article, hasnt he?It must have rained last night, didnt it?D: need and dare 过去时 dared情态动词和实意动词的区别A 人称变化 B do / to do C 直接否定 / 间接否定 can workNeed /dare 肯定句中，实义动词She needs to do it. I dare to do it.使用在否定句,疑问句中，情态动词，实义动词。I dare not do it. I dont dare (to) do it.I need not do it. I dont need to do it.1 need 情态动词 无时态；人称的变化 多用于疑问句和否定句You neednt try to explain.Neednt = dont have to Neednt have done sth 过去本不必做某事* 虚拟语气2 need 实义动词 有时态；人称的变化 后接to do You need to tell us the truth.The car needs repairing. The car needs to be repaired.3 dare 情态动词 过去时 dared 无人称的变化 多用在疑问句和否定句Dare he tell them what he knows?4 dare 实义动词 有时态；人称的变化后接to do用于疑问句和否定句时 其后的to 有时可省略Do you dare (to) jump off the high wall?E: will and would1 表示征求对方(第二人称)意见或询问对方意愿 would 比will 更客气委婉Will you have some more wine?Would you mind my smoking here?2 will 表示习惯性动作或某种倾向 would 表示过去习惯性动作或某种倾向Fish will die out of water.When I was young, I would play badminton on Sundays.Would 与 used to 的区别*Would 只能用来表示重复的动作而不能表示状态Used to 既可表示动作也可表示状态, 强调现在不如此He used to be a university student.3 will 表示意愿 决心I will never do that again.F: shall, should and ought to1 shall 在问句中表示征求对方意见或请求 用于第一，三人称What shall we do now?2 shall 肯定句中 表示说话人强烈的感情 允许，命令，禁止和威胁 *或表示按规定，规章和义务等用于第二，三人称If you dare to do that, you shall be punished.These rules shall be obeyed. Shall not 禁止，不许3 shall 决心，意愿 = willI shall come if I want to.4 should 表示劝告，建议 = ought to 应该You should wash your hands first.Should 主要表示主观看法*Ought to 客观情况 法律、规定、义务的使用Should have done / ought to have done sth 虚拟语气*Shouldnt have done / ought not to have done sth You should have done it today.5 should 推测 推论 可能性 = ought to *估计They should/ ought to be there by now.6 should说话人的感情。如惊奇、愤怒、失望等、“竟然” 否定句疑问句You cant imagine that well-behaved gentleman should be so rude to a ladyWhy should he do such a thing?情态动词数量不多,但用途广泛,主要有下列: can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would),have (to) ,had better. 情态动词还有一个很重要的用法，即情态动词表推测情态动词表推测的用法小结（一）情态动词表推测的三种句式 1.在肯定句中一般用must (一定)，may（可能），might / could（也许，或许）。 www.gkxx.com（1）He must/may/might know the answer to this question? 他一定/可能/也许知道这个问题的答案。 （2）It is cold in the room. They must have turned off the heating. 屋里很冷，他们肯定把暖气关了。 2.否定句中用cant / couldnt(不可能), may not/might not(可能不)。 Must not 不准（1）It cant/couldnt be the headmaster. He has gone to America. 这不可能是校长，他去美国了。 （2）He may not/might not know the scientist. 他也许不认识那位科学家。 3.疑问句中用can/could (能?)。 （1）Could he have finished the task? 他可能把任务完成了吗？ （2）Can he be at home now? 他现在能在家吗？ Can不肯may不问must肯定不否问注：以上三种句式中情态动词的语气按程度都是依次递减的。Might, could并非may, can的过去式，而表示语气较为委婉或可能性较小。 （二）情态动词表推测的三种时态 1.对将来情况的推测，用“情态动词 + 动词原形”。 （1）She must / may / might / could arrive before 5. 5:00前她一定/可能/也许到。 （2）She must/may/might/could walk miles and miles among the hills without meeting anyone. 她一定/可能/也许会在山里一连走好几英里而遇不到一个人。 2.对现在或一般情况的推测，用“情态动词 + be”，“情态动词 +be doing”或“情态动词 + 动词原形”。 （1）He must / may / might / could be listening to the radio now. 他一定/可能/也许正在听收音机。 （2）He cant ( couldnt ) / may ( might ) not be at home at this time. 这个时候他不可能/可能不在家。 （3）Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony ? 布什先生一向准时，这次开幕式他怎么可能迟到呢？ 3.对过去情况的推测，用“情态动词 + have +过去分词”。 （1）It must / may / might / could have rained last night .The ground is wet. 地湿了，昨晚肯定/可能/也许下雨了。 （2）The door was locked. He can ( could ) not / may ( might ) not have been at home . 门锁着，他不可能/可能不在家。 （3）Can / Could he have gotten the book？ 难道他找到书了吗？ 注：情态动词 should /ought to表推测时，意为“想必会，理应”但与“have +过去分词”连用时，则又可构成虚拟语气意为“本应该做某事却没做”。例如： （4）Its seven oclock. Jack should/ought to be here at any moment. 现在七点钟了，杰克理应随时到达。（推测） （5）She should / ought to have attended your birthday party, but she had to look after her mother in hospital. （虚拟） 她本该出席你的生日晚会的，可是她得在医院照顾她妈妈。 （6）Tom should not /ought not to have told me your secret, but he meant no harm. （虚拟） 汤姆本不该告诉我你的秘密，可是他并无恶意情态动词+完成式对过去或完成的猜测must / may /might / could / cant / couldnt/can?/could? have done 虚拟语气could have done 本来可以；有可能neednt have done 本没必要做某事should / ought to have done 本应该做某事shouldnt / oughtnt to have done本不应该做某事 must have done一定做了