英语语法
情态动词 情态动词
情态动词是高考的重点考查项目，对学习情态动词的要求是：
首先、了解情态动词各自的基本意义及用法，然后掌握情态动词表示推测的用法（其中重点是对表过去推测的用法）还要注意带有情态动词的反意疑问句的用法。
情态动词的特征：
1.本身有词义，但完全。因此不能独立作谓语，只能和动词原形一起构成谓语。
2.后接动词不定式一律不带to
3.不随人称和数的变化。
情态动词各自的基本意义及用法
表一、can 与could用法对比表
对比点 can could
1、表“能力” Can you lift this heavy box? I couldn?t understand what he said at all.
2、表“许可” You can use a different material instead. He said I could borrow his bike.
3、“怀疑” No, no, it can?t be true.
What on earth can this mean? We thought the story could not be true. How could you be so careless?
4、can与be able to 区别 1. could代替 can，表示语气更为婉转。
Eg. Could I use your bike? Yes, I can
2. can (能够)=be able to(仅表能力时)，但be able to 表示一番努力后，才能做得到，且有更多的时态。
He was a good swimmer, so he __________ swim to the river bank when the boat sank.
A. could B. might C. shall D. was able to
表二、may与 might用法对比表
对比点 may Might
1．表“询问” May I …?(=Can I …?) Might I …?(=Could I…?)(但比用may 更客气)
2.表“允许” You may take the boy there. He told me he might come .(might 与told相呼应)
3．表“可能”“或许” She may nor like this place. I?m afraid he might not like this play. 注： 1. May I…?的答语。
2.may可表示期望或祝愿
May you succeed !
3.may (might)用于目的状语从句中 肯定：Yes, you may.
否定：No, you mustn?t 不行（语气强硬）
No, you may not 或No, you?d better not.
The emperor gave them some gold in order that they might begin their work at once.
表三、must与have to的用法对比表
对比点 must have to
1．表“必须” （主观看法）必须；没有过去式，可用于间接引语中。He told me I must do according
to what he said. （客观需要）不得不，有多种时态。It?s raining heavily, we can?t go now.
2.疑问句 Must I …?
Yes, you must.（一定）
No, you needn?t./ you don?t have to.(不必) Do you have to go today?
Yes, we do.
否定句：You don?t have to worry about that.
表四、need与dare的用法对比表
对比点 need dare
1.情态动词+动词原形
1）否定式
2）疑问式 He need not (needn?t)go.
----Need we do it again?
---No, you needn?t do it again. He dare not say so.
Dare she go out alone at night?
How dare you say I?m unfair?
If he dare do that, he?ll be punished.(条件句)
I dare say.(固定用法)
2.行为动词+带to不定式
1）肯定式
2）否定式
3）疑问式 He needs to go.
He doesn?t (does not)need to go.
Does he need to do it again?
No, he doesn?t need ot do it again. He dares to say.
He does not(doesn?t)dare to say.
If you dare to jump into the water from here, so dare I .
3. did not need to do
表示过去没有必要做 She didn?t need to attend the meeting yesterday, and she stayed with her children.(她没有参加)
表五、should与ought to用法对比表
对比点 should ought to
1、表“应该” 表劝告、建议
You should listen to the doctor?s advice.
We should learn from Zhang Hua 表示“有责任有必要”做某事
You ought to finish your work before you go home.
We ought to help each other.
2、表“估计”
They should get home by now. 表示“非常可能”的事，可译为“总应该”
If we start to work right now, we ought to finish it before lunch.(午饭前应当能干完)
注： 1）、should还可在虚拟语气中的使用
2). 注意：ought to的疑问式及否定式
----Ought he to go? ----Yes, I think he ought to.
No, he oughtn?t to.
否定式：ought not to a或oughtn?t to do(不说ought to not do)
反疑问句：oughtn?t ______?
表六、shall与will的用法对比表
shall Will
1. 征询对方意见或请求指示，用于第一、三人称：
Shall I (we)…?
Shall he (she)…?
Where shall I (we)wait for you? 1． 询问对方的意思或向对方提出要求：
Will you(please)…? Won?t you…?
Would you like to…?(用would替代will更客气)
----Won?t you go and see the film?你不去看电影吗？---Yes, I think I will. 不， 我想去。
2. 表示说话人的“意愿”有“命令”“警告”“强制”“允诺”“决心”等，用于第二、三人称，要重读。 You shall do what I tell you ( to do).
我叫你干什么你就干什么。
Everything shall be done to save the ship.
一定要竭尽全力来拯救这艘船。 表示“意志”“意愿”，用于各种人称：
I won?t do anything you don?t like.
我不会做任何你不喜欢的事。
Would表示过去时间的“意志”“意愿”
Shylock would not take the money earlier.
夏洛克先前是不肯要钱的。
表七：used to与would用法对比表
used to would
1.表示过去的动作、状态，重在与现在情况的对比，不一定要有时间状语。
I used to play cards a lot, but now I seldom play.
My hometown is not what it used to be. 1.只表示过去动作的重复，有明确的时间状语 I would go to see my grandfather on Sunday when he was in the middle school.
2.would 后只接表动作的动词，不接表认识或状态动词
He used to be nervous in the exam.
2.表示过去的习惯有时可互换：
When we were very young, we used to / would go skating every winter.
2. 表示过去的次数时，不能使用：
( √）We went to the Great Wall five times when we were young.
( X ) We used to go / would go to the Great Wall five times when we were young.
注：used to do的否定式：usedn?t to do 或didn?t use to do (usedn?t也可写作usen?t) 疑问式： Did you use to do ? Didn?t you use to do?
Used you to do? Usedn?t you to do?
情态动词表推测
情态动词表推测的意义：
1、大多数情态动词（除表?能力、许可、意志?外），都可以表示推测，其程度有差异。按其可能性程度的高低排列为：
Must ﹥will ﹥would ﹥ought to ﹥ should ﹥ can ﹥ could﹥ may ﹥ might
肯定 完全可能 很可能 可能 有可能
2.注意区分情态动词的否定的含义：
may not或许不、可能不 might not可能不 can?t 不可能
mustn?t不许、禁止 shouldn?t不应该 needn?t 不必
3.情态动词表推测具体运用：情态动词可以对现在、进行、过去推测
S主+情态动词+be+adj 对“性质”“特征”的推测
S主+情态动词+be+n 对“职业”“事物”的推测
S主+情态动词+V原 对经常性行为的推测
S主+情态动词+be+V-ing 对进行着的行为的推测
S主+情态动词+have+PP 对过去的行为的推测
特别提醒：情态动词表推测时
1、 can只能用于否定句和疑问句
2、 must只能用于肯定句（它的否定句和疑问句其实就用can来代替了）
3、 如句中有情态动词 + 完成时，定是对过去的推测 。
4、 句中如有表示不肯定的话语，如：I am not sure; I don?t know 之类，常选may /might的各种形式
4. 记住下面几组表示反劝的特殊的表推测的形式
1). could + have + PP表示本来能做到，但事实上没有做到。 He could have finished the task on time, but the heavy snow came.
2). couldn?t +have + PP表示本来不能做到，但已经做到了。 She could not have covered the whole distance, but in fact she arrived ahead of time.
3) needn?t + have + pp表示本不必做的，但已经做到了。 She needn?t have attended the meeting yesterday, but she did.
4.) should/ought to +have + PP表示 该做而没有做 The plant is dead. I should/ought to have given ot more water.
5) shouldn?t/ oughtn?t to +have + PP表示 不该做而做了。 You oughtn?t to / shouldn?t have taken her bike without permission.
5. 记住下面对比表：
must只能用于肯定句（它的否定句和疑问句其实就用can来代替了）
1.must + have + PP 表示对过去肯定的推测，译为“一定是，准是” The road is wet. It must have rained yesterday.
2.can + have + PP 表示对过去的推测（限于问句中） Can she have said so? 他可能这样说吗？
3.can?t + have + PP 表示对过去的否定推测 He cannot have said such a foolish thing. 情态动词表推测的反意疑问句
情态动词表推测的反意疑问句，简单来说，就是以情态动词后的时态为淮，如句子里有明确
的时间状语，则以其为准。以 must 为例：
eg. 1. You must be hungry now, aren?t you?
2. He must be watching TV , isn?t he ?
3 Tom must have lived her for a long time, hasn?t he ?
4. She must have arrived yesterday, didn?t she?
注：如选择题中（以She must have arrived yesterday, didn?t she？为例）既有didn?t she又有hasn?t she则以didn?t she？为最佳答案。
第二篇：高中英语语法 情态动词
第六章 情态动词
一.概念:
情态动词是表示能力,义务,必须,猜测等说话人的语气或情态的动词.
二.相关知识点精讲:
1．can
1)表能力
can表能力时意味着凭体力或脑力或技术等可以无甚阻力地去做某事。
I can climb this pole. 我能爬这根杆子。
He is only four , but he can read. 他只有4岁，但已认得字了。
Fire can’t destroy gold. 火烧不毁金子。
因为can不能和其他助动词连用，所以表示将来式时用will be able to
You will be able to skate after you have practiced it two or three times.
你练习两三次后就会溜冰了。
2)表可能性
多用于否定与疑问结构中，但也可用在肯定句中。
Can the news be true? 这消息可能是真的吗？
It can’t be true. 它不可能是真的。
What can he possibly mean? 他可能是什么意思？
can 用在肯定句中表示理论上的可能性（一时的可能）。
A horse in the center of London can cost a lot of money.
Attending the ball can be very exciting.
The road can be blocked. 这条路可能会不通的。
may 在肯定句中表示现实的可能性。
The road may be blocked. 这条路可能不通了。
3)表示允许（和may意思相近）常见于口语。
Can (May) I come in ? 我能进来吗？
Can I smoke here ? 我可以在这里抽烟吗？
2.could的用法
1)表过去的可能和许可，（多用于间接引语中）
At that time we thought the story could not be true.
那时我们认为所说的事不可能是真的。
Father said I could swim in the river.
爸爸说我可以在河里游泳。
2)表过去的能力
I could swim when I was only six.
我刚六岁就能游泳。
Could在肯定句中表示过去的能力时，常表抽象的一般的能力。
He could be very naughty when he was a child.
他小时候会是很顽皮的。
3)表“允许”。可表示委婉客气的提出问题或陈述看法
Could I use your bike?
Yes, you can.
他会记得那时吗?
I’m afraid I couldn’t give you an answer today.
恐怕我今天不能回答你。
The teacher said you could go to the store for sweets.
老师说你可以去商店买糖。
3)Could/can+have done 结构表示对过去发生的事情的“怀疑”或“不肯定”。 could 加完成式还用于肯定句时一般表过去可能完成而却未完成的动作。
Can they have won the basketball match？
他们赢了那场篮球赛吗？
What you referred to just now can have made her very sad.
你刚刚所谈到的可能令他很伤心。
You could have completed the task a little earlier.
你本来能早点完成任务的。（但事实上并没有提前完成任务）
I could have passed my examination easily but I made too many stupid mistakes. 我本可以轻易通过考试，但我犯了太多不该犯的错误。
如表具体做某一件事的能力时，则须用 be able to .
He was able to translate the article without a dictionary.
他可以不用词典翻译那篇文章。
Can表示一贯的能力 ，be able to表示客观能力和通过努力可以达到的能力
I can’t swim. But I am sure I will be able to swim through more practicing.
The fire spread through the hotel, but everyone was able to get out
When the boat sank he was able to swim to the bank
3.may 的用法
1)表示请求、可以、允许。
You may drive the tractor. 你可以开那台拖拉机。
2)当回答由may 引起的问题时，否定答语要用must not,表示“不许可”、“不应该”、“不行”。May I come in?
Yes, you may.
No,you can’t
No, you may not .
No ,you mustn’t
No ,you’d better not.
3) may /might 推测性用法 可能
He may be right.
He may not come today (可能不)
He may /might come tomorrow.
, 注意: 1只用于肯定和否定句中,不用于疑问句中。
2 might 比may可能性更小
He might get a job.
He may get a job.
3 may no 可能不 can not不可能
He may not come
He can’t come
3)表建议（可和as well 连用）
You may（might）as well stay where you are.
你还是原地待着好。（may as well 有“还是……的好”的含义）
4)表祝愿
May you be happy!
might
1)表过去的“可能”和“允许”多用于间接引语。
She said that he might take her dictionary.
她说他可以拿她的词典去用。
除在间接引语中外，might一般不表示过去的“可能”与“许可”。表过去的“可能”可用could，表过去的“许可”可用were (was) allowed to。
2)表现在的“可能”，其可能性要比may小。
Electric irons could be dangerous; they might give you a severe shock.
电熨斗会有危险，它可能电着人。
3)may (might) + have +done 表示对过去发生行为的推测，含有“想必”、“也许是”的意思。 It may have been true. 这事也许是真的。
He might not have settled the question. 他可能尚未解决那个问题。
4.must 的主要用法。
1)表示必须、必要
We must do everything step by step .我们必须按部就班地做一切事情。
Why must you always bother me? 为什么你偏要打扰我呢。
2)must be + 表语的结构，通常表示猜测，含有“一定”之意。（只用在肯定句中）
He must be an honest boy. 他一定是个诚实的男孩。
This must be your room. 这一定是你的房间。
3)must 的否定式有两个：当回答由must引起的问题时，否定答复要用needn’t或don’t have to 表示“不必”、“无须”、“用不着”、“不一定”的意义。当表示“不应该”、“不许可”、“禁止”时，就用must not。 Must I go tomorrow?明天我必须去吗？
Yes, please.是的，请吧！
No , you needn’t. 不，你不必去。
4)must +have +过去分词的结构，常用在肯定句中，表示对过去发生行为的推测，含有“一定”、“准是”的意思。否定和疑问句用can。
She must have studied English before.她以前一定学过英语。
5.have to的含义与must是很接近的,只是have to 比较强调客观需要，must着重说明主观看法。 I must clean the room.（主观想法）
I have to clean the room.（客观需要）
另外，have to 能用于更多时态：
We had to be there at ten .我们得在十点钟到那里。
We will have to reconsider the whole thing.
这一切我们将不得不重新加以考虑。
have to 的否定式：don’t have to do 表示“不必做……”之意。
6.ought to 的用法
Ought to 后接动词原形，表义务，但不及must 那样具有信心，如：
You don’t look well. You ought to go to see the doctor.
你气色不好，应该去看病。
Ought to 用于否定句，其否定形式可缩略为oughtn’t ，如：
You oughtn’t to smoke so much. 你不应该抽这么多烟。
也可以用于疑问句，如：
Ought you to smoke so much?你应该抽这样多烟吗？
Ought to 在间接引语中表过去时形式不变，如：
He said you ought to tell the police.
他说你应该去报告警察。
7.shall的用法
1)用于第一人称征求对方的意见，如：
What shall I wear on the journey? 我路上穿什么好呢？
Shall we dance? 我们跳舞好吗？
2)shall 用于第二、三人称时表允诺，警告，命令，威胁（现已少见），如：
She shall get her share. 她可以得到她的一份。
You shall have it back tomorrow.你明天可以将它拿回。
情态动词should一般不应被认为是情态动词shall的过去式，主要用法有：
1)用于第一人称疑问句中询问对方的意愿，但语气较委婉温和，如：
What should we do now? 我们现在该怎么办？
2)表示应该、必须，常与must 换用。例如：
We should (must) master a foreign language at least.
我们应当至少掌握一门外语。
3)“should+be+表语”的结构，表示推测或惊奇。例如：
They should be back by now. 他们现在应该回来了吧。
I am sorry that she should be so careless. 我感到遗憾她竟会那样粗心。
4)“should+have+过去分词”的结构，表示过去该做而实际上尚未做的动作或行为；其否定则表示发生了不应该发生的行为。其同义结构“ought to have +过去分词”,表示过去“早应该”、“本当”之意，语气较强。例如：
I should have thought of that. 这一点我是应当想到的。（但没想到）
They should not have left so soon.他们不应当走得这么早。（但已走了）
5) 在“It is natural (strange, natural, necessary, surprised, impossible, important ) that……”句型中，主语从句中的谓语动词要用should +动词原形”表示“理所当然”、“奇怪”、“必要”、“惊异”等的意思。在lest（以免）、for fear (that) (以防)、in case（以备万一）等之后也要用should+动词原形;在advise, sugest, order, demand, request 等的从句中should+do”例如：
It is necessary that he(should) be sent there at once.
有必要马上派他到那里去。
It is strange that he should say so. 他会说这样的话真是奇怪。
Let us go at once lest we should be late for the train.
我们马上走吧，以免赶不上火车。
8..will和would的用法
1）表示意志，决心或愿望。例如：
Surely we will support all the people in the world in their struggle for peace.
我们一定要支持全世界人民争取和平的斗争。
He would not let me try it . 他不肯让我去试。
2）will表示经常性、习惯性、倾向性，would表示过去的习惯行为。
He will sit there hour after hour looking at the traffic go by.
他会经常一连几个小时坐在那儿观看来往的车辆。
He would come to see me when he was in Beijing.
他在北京时，常来看望我。
3）用于第二人称作主语的疑问句中，表示对对方的请求，would的语气比will委碗 Would/will you kindly tell me the way to the station? 请问到火车站怎么走？
4）表可能性
This will be the book you are looking for.
这可能就是你要找的书。
She eould be about 60 when she died.
他死时大概60岁。
9. need和dare的用法
情态动词need 实义动词 need
现 You need (not) do You (don’t) need to do
在
时 He need (not) do He needs (doesn’t need) to do
过 You needed (didn’t need) to do
去
时 He needed (didn’t need) to do
将 You need (not) do You will (not) need to do
来
时 He need (not) do He will (not) need to do
句型 时态 动词
情态动词dare 实义动词 dare
肯定句 现在时 dare to 少用 dare/dares to do
过去时 dare to 少用 dared to do
否定句 现在时 daren’t/dare not do do/does not dare (to) do
过去时 dared not do did not dare (to) do
疑问句 现在时 Dare he do? Do you/Does he dear (to) do?
过去时 Dared he do? Did he dare (to) do
needn’t have v-ed 表示过去做了某事，但没有做的必要， 意为“本没必要…”。例如：You needn’t have waken me up; I don’t have to go to work today
10.表推测的情态动词句子的反意疑问句
He must/may be in the room, isn’t he?
He can’t be in the room, is he？
He must have finished the work, hasn’t he?
He may have done the work last night, didn’t he?