英语语法讲解——情态动词：doc全文下载 href="/Upload/UploadFiles//coach_UploadFiles_8112/201311/2013112509592436.doc">高考英语语法讲解——情态动词：doc全文下载
情态动词
概述：情态动词表示说话人的情感态度。它有一定的实在词义（如：能、会、可能、以前、最好、宁愿），只有谓语特性，必须和其他动词一起构成谓语。
中学阶段常见的情态动词:
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情态动词 |
can(could) may(might) must will(would) shall should ought to had better would rather need dare |
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与情态动词相关的短语 |
be able to have to used to |
情态动词的固定谓语结构：情态动词+（不带to）动词不定式形式do
+be doing
must +have done
+have been done
+have been doing
注意：ought (to)和used ( to)例外，动词不定式要带上”to”
一、情态动词的用法：
1．can
1）表示能力“能够，会”
She can drive, but she can’t ride a bicycle.
Can you give me a lift to the station?
2）表示对现在动作或状态进行主观的猜测“可能、会”，或表示惊异，怀疑，不相信等态度，主要用在否定句、疑问句或感叹句中。例如：
He can’t have a lot of money.
Can it be that it was I, not he, who was mistaken?
How can you be so careless!
3）表示客观可能性“可能”，可用于肯定句
As a human being, anyone can make a mistake.
The temperature can fall to
4）表示允许“可以”，意思与may 相近，主要用在口语中
Can I have a look at your copy of China Daily?
This sort of thing can’t go on .
5）构成下列特殊句式：
①cannot /can never …too … 或 cannot …enough越…越好；非常．．．．．．
One cannot be too careful.
I cannot thank you enough.
You can’t praise him too highly.
②cannot help doing …/cannot help but do …/cannot but do …禁不住；不由得；不得不
I cannot help admiring the picture whenever I look at it.
When a close friend dies, you cannot but feel sad.
2. could
1)表示能力,指的是过去时间
In those days few workers could support their family .
I couldn’t follow the teacher in class.
2)表示允许,指的是过去时间
She asked whether she could take the books out of the reading-room.
3)表示可能,可以指过去时间;也可以指现在时间,表示语气缓和
I didn't think the story could be true.
But you mustn’t smoke while you’re walking around in the bush either. You could start a fire.
He looks young .He couldn’t be over fifty .他看起来很年轻,他不可能超过五十岁.
4)比较委婉客气地提出问题或陈述看法,指的是现在时间
Could I see your license?
I have a few friends. I could ring to see if they’re free .
Can(could)与be able to
Can (could)和be able to表示能力时意思上没有区别.但can 只有现在式和过去式,而be able to 则有更多的形式.
No one is able to do it. = No one can do it.
Will you be able to come tonight?
I’m sorry I haven’t been able to answer your letter.
She said she had not been able to come earlier.
但是,在表示成功地完成某一具体动作时用be able to 来表示。这时,be able to相当于managed to 或succeeded in doing ,表示经过一番努力，终于能够……。例如：
people 2）Managed to escape into the street .
3）succeed in escaping
3．May
1)表示许诺“可以”或询问、说明一件事。
注意：回答may 引起的问句时，否定形式用must not (禁止)，had better not (最好别)。
May I trouble you with a question?
—Could I call you by your first name ?
—Yes, you may. /No, you mustn’t. /No, you’d better not.
2).表示表示主观的推测“或许”，通常用在肯定句和否定句中。例如：
He may be very busy now.
He may not be at home.
注意：表示可能性时，can’t 语气强表示“不可能”；may not 语气弱，表示“可能不（或许）”。
4．might
1)表示可以做的事，指的是过去时间
He asked if he might look through my album.
2）表示口气比较婉转客气，指的是现在时间
Might I ask for a photograph of your baby?
I wonder if I might borrow some coffee.
3）表示可能发生的事，可以指过去时间；也可以指现在时间，但表示语气更加不肯定
She was afraid they might not like the idea.
They might have a lot of work to do now but I’m not sure.
5．must
1)表示必须要做的事，否定表示“禁止”
We mustn’t move someone if they are badly hurt. 如果一个人受了重伤，你一定不要挪动他。
注意：在回答由must 引起的问句时，如果是否定回答，不能用mustn’t ,而要用needn’t 或don’t have to ,因为mustn’t 是“不准、禁止”的意思。
-- Must we send in our plan this week? --Yes ,you must .。
--No, you needn’t. / No, you don’t have to .
2）表示猜测，意为“想必，准是，一定”，只用于肯定句中
This must be your room.
Look at his new car. He must have a lot of money.
3)表示讨厌情绪“偏偏”
I am sleeping when you must turn your radio on.
注意：have to 表示“必须”，“不得不”，在这个意义上与must 很接近，但must 表示的是说话人的主观看法，而 have to表示的却是客观需要。另外，have to比must 有更多的形式。
You must be back by ten.（命令或叮嘱）
You have to be back by ten. （客观需要）
We had to go home on foot. 我们不得不走回家。
6．should 和 ought to “应该”
1)表示应该做的事，should 和 ought to 一般可以通用。但ought to 语气更强些，强调“有责任，有义务做”或“按道理应该如何”；should 含有“劝告、建议”的语气，即“按我的想法应该如何”。试比较
-- I’ll start the work tomorrow .我明天开始这工作。
--Ｉthink you should start at once./ No, you ought to start at once. 不行，你得立即开始。
2）表示推测，意为“想必一定，照说应该，估计”。should 和 ought to 在这一意义上含义比must 弱。试比较
Mr. Black must be home by now.（肯定）
Mr. Black ought to (should) be home by now.（不能肯定）
7．shall
1) 用于第一、三人称，构成疑问句，表示征求对方意见或请求指示
Shall I open the window?
Shall the boy wait outside?
2)用于第二、三人称，表示说话人的意愿，表示“命令、警告、威胁、强制、允诺、决心”
You shall do as I say.（命令）
Tell him that he shall have the book tomorrow.（允诺）
If you children don’t do as I tell you, you shall not go to the party .（威胁）
You shall be sorry for what you did. 对你的所作所为你会感到后悔的。（警告）
Nothing shall stop us from carrying out this plan. 什么也不能阻止我们实现这项计划。（决心）
8．will
1)表示“意志，意愿”，可用于多种人称
I will do anything for our soldiers.
If you will read the book, I will lend it to you. 如果你愿意读这本书，我会把它借给你。
注意：从句中的will 是情态动词 ，表示“意愿”；主句中的will 是助动词，帮助构成将来时。
2）will 在疑问句中用于第二人称，表示询问对方的意愿或向对方提出请求
Will you open the door for me, please?
Pass me the glass, will you? 递给我杯子，好吗？
有时，这种句子也可以是won’t you have a little more rice ?
3）表示某种倾向或习惯性动作，意为“总是会，老是，就是”；否定结构意为“不肯、不能”。这种用法并不指将来时间，因此，不能与表示将来时间的状语连用
Some birds will fly south when winter comes.
Boys will be boys. They are always naughty.
What’s the matter with the door? It won’t lock.
9．would
1) 是will 的过去式，表示过去时间的“意志、意愿”，可用于多种人称
They said that they would help us.
2）would 指的是现在时间，表示说话人的意愿或向对方提出请求，语气比will 婉转。也可表示委婉地提出看法、请求、建议等
I would like to have a try. 我想试试。
Would you like me to carry it for you? 我帮你拿这个好吗？
3）表示反复发生的动作或过去的一种倾向
He told me the box wouldn’t open . 他告诉我盒子就是打不开。
10 .used to
在肯定句中，used to 表示过去（曾经）的动作或状态，现在“已不”.
I used to get along very well with my cousin and we used to be very good friends.
Did you use to go to the same school?
I didn’t use to smoke.
John used to be a policeman, didn’t he?
Did you use to take a walk in the morning?
used to 常用来表示表示已不复存在的过去的习惯，侧重与现在的对比，而would用来表示过去反复发生的动作。
He would go to that bookstore when he was at college. 他在上大学时经常去那个书店。
11． need
need 作为情态动词，主要用于否定句，疑问句中。在肯定句中一般为行为动词
Need he do it all at once? 他需要马上做这件事吗？
Why need you go today? 为什么你今天需要去？
I wonder if I need bring my computer .我想知道我是否需要带上电脑。
注意：回答由need 引起的问句时，肯定回答一般用must ,否定回答时用needn’t.
--Need I give you the book?
--Yes ,you must .
--No ,you needn’t .
need 用作及物动词，和不定式连用，可用于各种结构。
Does he need to know it?
The question needs to be discussed .这问题需要讨论。
12. dare (dared )
dare及其过去式dared 作为情态动词，主要用于疑问句、否定句和条件状语从句中。
Dare you go home alone?
She dare not say what she thinks.
除了在I dare say … 这种习惯用语中，dare 在肯定结构中用作情态动词的情形是很少的。
I dare say my uncle will do that.
dare 还可以作及物动词，跟不定式，用于各种结构。否定句中to 可以省略。
We must dare to act.
I did not dare (to )look up .我不敢抬头看。
二、情态动词的完成式（表示已经发生的情况和表示虚拟语气）
1、must have+过去分词，表示对已发生情况的肯定推测
My pen must have apparent the moment I walked into the room.
2、can’t / couldn’t have+过去分词，表示对已发生情况的否定推测
Mary can’t have received my letter; otherwise she would have replied before now.
3、may / might have +过去分词，表示对已发生的事情做不肯定的推测
A potentially serious leakage of radioactive water may have been caused by an electrician.
4、needn’t have + 过去分词，表示做了不必做的事，相当于“didn’t need to do” As it turned out to be a small house party, we needn’t have dressed up so formally.
5、should have +过去分词，表示应该做某事但实际上未做
I should have planned everything ahead carefully.
6、could have +过去分词，表示过去本来可以做但却未做
You could have phrased it more tactfully
7、may/ might have +过去分词，表示过去可以做但实际未做
It might have been better to include more punchy statistics and photos of equipment in the introduction to further assist first-time office automation managers.
三、其他
情态动词must ,can/could ,may /might 表推测句子的反义问句的构成。要先将情态动词去掉按照常规句子的方式进行变换。例如：
He must be working in the office now, isn’t he?
Tom may have missed the bus again, hasn’t he?
Jack can’t have arrived this morning, did he?
如果是祈使句，则都变成 will sb？
情态动词DCDAA CBBDB CBBB
虚拟语气补充DBCAA BCDDA CDADA BBDAB
