情态动词小结(共五则)
情态动词小结（共五则）
第一篇：情态动词小结
情态动词小结
情态动词有：can（could），may（might），must，have to, shall（should），will（would），need, dare, ought to等。一． 情态动词can, may, must用法 ㈠基本用法 1.can ⑴ 会，能够--Can you swim?--Yes, I can.--No, I can‟t.⑵ 口语中代替may.You can(may)park here.你可以把车停在这里。(许可)2.may允许，许可--May I come in?--Yes, you may./Sure, come on in.--No, you mustn‟t./No, you can‟t.No, you‟d better not.3.must必须--Must we finish the exercise today?--Yes, you must.--No, you needn‟t./No, you don‟t have d 需要，必需--Need you go now?=--Must you go now?--Yes, I must.--Yes, I must.--No, I needn‟t.--No, I needn‟t.(need作为情态动词，通常用在否定句和疑问句中。)注意一：can 与be able to 都可以表示“能力”，区别是： ⑴ can只有现在和过去两种形式
I can play the piano.She couldn‟t play the piano when she was a little girl.⑵ be able to ① 有更多的形式和时态
We shall/will be able to finish the work next week.I haven‟t been able to find the book.② 指具体一次活动
I can swim but I am not able to cross the rough sea.有时两者可以互换: I‟m not able to(can‟t)answer your question.Are you able to(Can you)type(打字)？
注意二：could的用法
⑴ 作为can的过去式，表示过去的能力。
When I was young I could climb any tree in the forest.这时也可用was(were)able to ⑵ 用来代替can，婉转地提出请求，想法，建议等。回答这种情况下could引导的一般疑问句时，不用could，而要用can。A: Could you tell me how to get to the hospital? B: Of cause, I can.注意三：must的否定形式表示“不得”，“一定不要”，“禁止” ① You mustn‟t take photos in here.It‟s forbidden(禁止).② You mustn‟t drive without a license（驾照）.③ We mustn‟t be late, must we？
（与第4页对比，此must不表猜测,两回事。）注意四：must的过去式是must，常用 had to
代替。I had to see the dentist.注意五：must 和 have to 都可以表示必须，但must表示说话人的主观看法，have to表示客观需要。You must say sorry to me for that.You have to drive quickly, we have little time.注意六：May+动词原形表“祝愿”。
May you succeed.May you be happy every day.㈡ 可能性用法
1.can表示“可能性”① 疑问句：只能用can
Who can it be ?
② 否定句：cannot(can‟t)“不可能 It cannot be Jenny.2.may表示“可能性”① 否定句：may not“可能不”
It may not be Jenny.② 肯定句：“大概”，“也许”，“可能” It may be Jenny.3.must表示“可能性”，只能用于肯定句，表推测：“一定是”，“准是”，“必是”，“必定”。
It must be Jenny.小结表示“可能性”：
疑问句：只能用can 否定句：cannot(can‟t)“不可能”(反义词是must“准是”)may not“可能不”
肯定句：may “大概”
must“准是”(反义词是can‟t)注意一: 在表示“可能性”时，凡是对过去事物的猜测，不管是疑问．．句，否定句还是肯定句，都要用完成时。．．．① It must have rained last night.You see, the ground is still wet.② He can‟t have been to your home.He doesn‟t know your address注意二：may+原型 表示 现在或将来的可能性。若表示对过去事物 ．．．． 的猜测，则用完成时。③ He may come today.(tomorrow)He might come today.(tomorrow)(might语气更不肯定，不是may的过去时)④ She might have called for help.她可能大声喊“救命”了。请翻译下里句子：
1.Where can Wei Fang be? 2．That can‟t be Mary.She is in hospital.3.Surely you can‟t be hungry.You‟ve only just had lunch.4.The key can‟t be in the room.I have just searched it carefully.5.You may/ can go and ask him.But he may not answer you.6．A：Look！Someone is coming.Who can it be? B: It may be our headmaster.A: It can‟t be him.He has gone to Shanghai.B: It must be Mr.Zhang.He looks like our headmaster.7.Anna may know Tom‟s address.8.They may be waiting at the station.9.I may be going to Europe nex
t year.10．He may have gone abroad.11.I‟m afraid I must be going now.12.You must be hungry.Have something to eat.13.They must be twins.14.There‟s a lot noise from next door.They must be having party a party.15.I can‟t find him anywhere.He must have left.16.I can‟t find my book.I must have left it at home.17.You must have been thinking of something.18.A: We went to Hainan for the winter vacation.B: That must have been nice.注意三：must表示猜测时的反义疑问句
⑴ “must be +表语”的结构，must表示肯定猜测时，含有“准是”，“势必”，“一定”等意义时，反义疑问句用“isn‟t/aren‟t+主语” They must be hungry after the long walk, aren‟t they? ⑵ “must have done” 表示猜测时，反义疑问句用“haven‟t/hasn‟t +主语”或“didn‟t+主语”
① They must have studied English before, haven‟t they? ② She must have met a fairy(仙女), hasn‟t she? ③ You must have seen the film last week, didn‟t you? ．．．．．．．．解题秘笈：① 把must去掉 ② 时间状语 ③ 重新组成一新句子 ④ 按新句子的时态造反义疑问句
① You must have been to Beijing, ＿＿＿ ＿＿？
去掉must；无时状；重组成You have been to Beijing； 故答案为：haven‟t you ② You must have finished your homework yesterday, ．．．．．．．．．＿＿＿ ＿＿？去掉must；时状为yesterday;重组成 You finished your homework yesterday;故答案为：didn‟t you 二．情态动词need的用法
⑴ need 表示“需要”，“必需”。作为情态动词，通常用在否定句和疑问句中。
① He needn‟t pay for it.(情态动词)=He doesn‟t need to pay for it.(行为动词)②--Need you go now?=--Must you go now?--Yes, I must.--Yes, I must.--No, I needn‟t.--No, I needn‟t.⑵ need也可用作行为动词，其变化与一般动词相同。① We need to think it over.(肯定句)② Does he need to know it?=Need he know it? ③ She didncan的过去式‟t need to go.=She needn‟t go.⑶ 按句型背：
need doing=need to be done ① The door needs painting.=The door needs to be painted.② The old man needed looking after.= The old man needed to be looked after.三．情态动词dare的用法
⑴ dare 表示“敢” 作为情态动词，通常用于否定句，疑问句或条件句中。dare 作为情态动词只有两种形式:dare, dared(当主语是第三人称单数时，dare 不加s)① She dare not do so.(否定句)② Dare he do it?(一般疑问句)③ How dare you say I‟m unfair.(特殊疑问句)④ Jump if you dare.有胆量你就跳。（条件句）⑵ 除了在“I dare say…” 这种习惯用语中，dare 在肯定句中作 情态动词的情况是很少的。（特殊用法，口语中常用，按句型背）① I dare say you are wrong.② A: If you die, who will get your money？
B: I dare say my uncle will.I have no other relatives.(亲戚)⑶ dare 也可用作行为动词，其变化与一般动词相同。① Who dare to go? ② I don‟t dare(to)ask her.问：此句中的to 为什么可以省略？
答: 当dare 作为①行为动词②在否定句中(两个条件必须同时具备)，其后面的不定式可以省略to。又如： ③ We didn‟t dare(to)try a shot.四．情态动词shall和should的用法
⑴ shall 作为情态动词，用于二，三人称，表示说话人的意愿，有．．．．．．．．“命令”，“警告”，“威胁”，“强制”，“允诺”等意思。（一人称用 shall是将来时）

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