情态动词及其被动语态

中考复习八 情态动词及其被动语态
（一）情态动词概说
1．情态动词也是“辅助性”动词，用来表示说话人的语气或情态。

情态动词所表示的情态有：请求、命令、允诺、可能、需要、敢于、愿望、义务、能力等。

2．情态动词本身有词义，但词义不完全，不能单独用作谓语，没有人称和数的变化，且后面只跟动词原形。

如：
她会唱英文歌曲。

She cans sing an English song.（F）
She can sings an English song.（F）
She can sing an English song.（T）
3．有些情态动词的过去时与其原形相同，有些与原形不同。

(1) 与原形相同的有：
must --- must ought to --- ought to
(2) 与原形不同的有：
can --- could will --- would
may --- might shall --- should
need --- needed dare --- dared have to --- had to
4．大多数的情态动词后面可以用动词不定式（多不带to）的进行时、完成时或被动形式，如：may, can, must等。

（二）情态动词的种类：（见下表）
原 形过去式词 义
can could能
may might可以（或许）
must must(had
必须（不得不）
to)
will would愿意
shall should应该
need needed需要
dare dared敢于
（三）情态动词的否定形式：
cannot --- can’t could not --- couldn’t may not---mayn’t
might not--- mightn’t must not --- mustn’t will not --- won’t
would not --- wouldn’t need not --- needn’t shall not --- shan’t
should not --- shouldn’t ought not --- oughtn’t dare not --- daren’t
（四）常用情态动词的用法：
1．can与could
1）． can
（1）表示体力或脑力方面的“能力”，也能表示根据客观条件能做某事的“能力”。

He can drive.
Can you jump as far as he did?
I can’t catch up with Jim.
can与be able to二者都表示“能够”，区别是：can只有现在时和过去式，而be able to可用于各种时态。

如：
I’ll be able to speak French in half a year.
He hasn’t been able to finish it on time.
（2）表示允许：
You can go now.
Can I use your bike?
（3）表示推测：
Who can it be?
It can’t be true.
can表示猜测或怀疑只用于疑问句及否定句中。

2）． could
（1）can的过去式，表示过去有能力及过去的可能性。

He couldn’t climb up the mountain.
The news could be true.
（2）表示客气地请求或委婉地陈述意见。

Could you go skating with me tomorrow?
I’m afraid I couldn’t give you an answer tonight.
（3）表示惊异、怀疑、不相信等态度
How could he say that?
He couldn’t be in Beijing.
2．may与might
1）． may
（1）表示请求、许可、可以
—May I use your dictionary?
—Yes, please/certainly.
May I come in?
（2）表示推测说话人的猜测，认为某一事情“或许”或“可能”发生。

It may rain this afternoon.
I may leave for Hangzhou next week.
（3）may用于感叹句中可以表示祝愿或愿望。

May you do well!
May you have a good time!
2)． might
（1）用作may的过去式。

We didn’t know that he might be our new teacher.
The accident might happen the day before yesterday.
（2）替代may来表示现在时间的动作，主要于推测（但其可能性比may 更低）。

I’m afraid it might snow tomorrow.
You might meet him at the conference.
The movie might have finished now.
（3）委婉地表示请求（不是过去式）。

Might I ask you a question?
Might you go there with me?
3．must
（1）．表示义务，命令或必要。

Soldiers must obey orders.
We must be strict with ourselves.
（2）．表示肯定的推测：一定
He must be at home.（对现在的猜测）
I think you must have made a mistake.（对过去的猜测）
He must be our new teacher.
He can’t be our new teacher.
（3）此外还要弄清楚must与have to的区别
4．will与would
1）． will
（1）表示意愿、决心。

此时可用于各种人称。

He won’t come to see you.他不愿来见你。

（表示意愿）
I will try my best to catch up with her.我将尽最大努力赶上她。

（表示决心）
（2）表示请求，此时仅限于“will you (please)…？”句型中，仅用于第二人称和疑问句中。

Will you please buy me an English-Chinese dictionary when you go to the bookstore?
Will you have some rice?
2）． would
（1）will的过去式，表示过去的意愿和决心。

He said he would do everything for her, but she said she would never see him again.
They believed that we would help them.
（2）用于现在时，表示委婉地提出请求，建议或看法。

此时would的用法比will更加委婉。

Would you please show me the way to the museum?
I would like to say something about it.
will和would用于“劝某人接受……”时，只能用some，不能用any。

如：
Would you like some fish? 吃点鱼好吗？
5．shall与should
1）． shall
征求对方意见或请求，用于第一、三人称。

表示“要不要……？”、“……好吗？”
Shall I open the window?
Shall the doctor come?
2）． should
（1）should意思是“应该”，表示劝告或建议（=ought to）
You should wash your hands before dinner.
We should help each other.
（2）用来表示可能性或猜测。

He should be in the office now.
I should be right.
（3）should有时能表示说话人的情感等。

It’s funny that they should be confident.（表示轻视）
Why should I do that for you?（表示不满）
（4）should后接动词不定式（不加to）时，若用于肯定句，表示某件事本应该完成却未完成；若用于否定句，则表示某事不该发生却发生了。

You should have told us the truth.（应该告诉却没有）
He should have known the importance of it.应该知道却不知道） We shouldn’t have left so early.（不应该早出来，可已经做了）
6．need
1）need意思是“需要，必须”，主要用于否定句和关系问句中。

You needn’t come so early.
Need I take part in the Party?
2) need引导的疑问句，肯定回答时多用must，否定回答时用
needn’t。

Need he come?
Yes, he must.
No, he needn’t.
3) need后接名词做宾语时，表示“需要”某件事物，此时用作实义动词，与一般的实义动词用法完全一样。

如：
We need three apples.
He doesn’t need so many books.
7. ought
ought只有一种形式，后面常与to连用，意思是“应该”。

You ought to visit us often.
Sorry, I ought to leave now.
在表示“应该”时，ought to的语气比should要强，比must稍弱。

8. dare
1) dare意思是“敢”，用于肯定结构中时，后接加to的动词不定式。

The boy dared to climb up the tree.
She should dare to question her teacher.
2）dare用于否定句或疑问句中时，与大多数的情态动词一样，后接不带to的动词不定式。

Don't dare do that again!
The poor girl dare not go home.
9．had better
You had better see a doctor.
You had better not leave now.
Had I better wait for her?
英语专题 被动语态
一、被动语态概述
语态是动词的一种形式，用以说明主语与谓语动词之间的关系。

英语的语态共有两种：主动语态和被动语态。

主动语态表示主语是动作的执行者，被动语态表示主语是动作的承受者。

被动语态是动词的一种特殊形式，一般说来，只有需要动作对象的及物动词才有被动语态。

汉语往往用“被”、“受”、“给”等词来表示被动意义。

如：He opened the door.　他打开了这扇门。

（主动语态）
The door was opened.　这扇门被打开了。

（被动语态）
二、被动语态的构成
被动语态由“助动词be+及物动词的过去分词”构成。

被动语态的时态变化只改变be的形式，过去分词部分不变。

疑问式和否定式的变化也如此。

1、被动语态的时态较常见的八种，现以动词clean为例列表说明：
2、被动语态的句式变化：
以一般现在时和动词invite为例，列表说明被动语态的句式变化：
3、含有情态动词的被动语态
情态动词的被动语态结构为：情态动词+be+过去分词；
其时态及句型的变化仅由情态动词完成，“be+过去分词”部分不变。

如：Tables can be made of stone.　桌子可由石头制造。

Tables could be made of stone at that time.　那时桌子可由石头制造。

（一般过去时）
Can tables be made of stone? 桌子能用石头制造吗？（疑问句）
三、被动语态的用法：
1、不知道或没有必要指出谁是动作的执行者时。

如：The bridge was built last year.　这座桥是去年建造的。

He was elected chairman.　他被选为主席。

2、当更加强调动作的承受者时。

此时动作的执行者由by引导置于谓语动词之后，不需要时可以省略。

如：The room hasn't been cleaned yet.　房间还没有打扫。

The tiger was killed by him.　老虎被他杀死了。

3、当动作的执行者不是人时，多用被动语态。

如：The window was blown by wind.　窗户被风吹开了。

The whole village has been washed away by the flood.　整个村庄都被洪水冲走了。

4、表示客观的说明常用“It is + 过去分词”句型。

如：It is said that Lucy has gone abroad.　据说露茜已经出国了。

It is believed that he is a spy. (=He is believed to be a spy.)　大家相信他是个间谍。

其它常见的“It is + 过去分词+ that”句型还有：
It is reported that…据报道
It is said that…据说
It is believed that…大家相信
It is suggested that…有人建议
四、主动语态变为被动语态
转换图示：
1、主动语态变为被动语态的步骤：
(1)将主动句的宾语变为主语：
注意：
如果主动句的宾语是代词，需将其由宾格变为主格。

如：Tom killed him. → He was killed by Tom.
(2)将动词改为“be+过去分词”。

注意：
They held a meeting yesterday. → A meeting was held by them yesterday.
他们昨天开会了。

(3)将主动语态的主语改为by…放在谓语动词后。

注意：
如果原主语是代词，则应由主格变为宾格。

如：He sang a song. → A song was sung by him.
2、主动语态变为被动语态的注意事项：
(1)主动句中的主语如果是people, we, you, they, somebody等含糊地表示“人们”、“大家”的单词，变为被动句时，通常删去“by…”，但原主语被强调时除外。

如：They set up this hospital in 1975.→This hospital was set up in 1975.
这所医院建于1975年。

Only he can finish the job. → 只有他能完成这项工作。

The job can be finished only by him.这项工作只能由他来完成。

(2)含有双宾语，即直接宾语和间接宾语的句子，每个宾语都可变为被动语态的主语，即其被动语态有两种形式。

但多以间接宾语作主语。

如：Jack told us the truth.杰克告诉了我们真相。

We were told the truth by Jack.
The truth was told (to) us by Jack.
五、动词的主动形式表示被动之意
以主动形式表示被动之意的动词多为连系动词，
如：look，feel，smell等。

下列动词没有被动式：happen，cost，have
如：An accident was happened yesterday.（×）昨天发生了一起事
故。

An accident happened yesterday.（
）
The flower smells sweet.这花闻起来很香。

The watch looks good.这表看起来很好。

This book sells well.这本书畅销。

六、各种时态的被动语态举例（以动词do为例）
1．一般现在时（am/ is/ are +done）
如：English is spoken by lots of people in the world. 世界上的许多人都说英语。

Class meeting is held every Thursday. 每周四都举行班会。

The classroom is cleaned by the students every day. 学生们每天都打扫教室。

2．一般过去时(was/ were +done)
如：The cup was broken by the boy. 杯子被那个男孩打碎了。

He was saved at last. 他最终获救了。

My bike was stolen. 我的自行车被偷了。

3．一般将来时与过去将来时(will/ shall be +done；would/should be +done)
如：A speech will be given this afternoon. 今天下午有一个演讲。

A new road will be built next year. 明年要修一条新马路。

I thought thousands of people would be helped. 我认为将有数千人得到帮助。

4．现在进行时与过去进行时(am/ is/ are being +done；was/ were being +done)
如：The machine was being repaired at this time yesterday. 昨天这时，机器正在被修理。

The problem is being discussed now. 问题正在被讨论。

A bus is being pushed by the passengers. 路人正在推一辆公共汽车。

5．现在完成时(have/ has been + done)
如：Two hundred trees have been planted by now. 到现在为止，已经种了二百棵树了。

The book has been read many times by me. 这本书已经被我读了许多遍了。

Several soldiers have already been killed in the conflict.
在冲突中已经有几名士兵被杀害。

6．过去完成时(had been+done)
如：They said they had been invited to the party. 他们说他们已经被邀请参加晚会了。

She found the house had been destroyed by the storm. 她发现房子已经被暴风雨摧毁。

He had been tortured by the illness for many years before he died. 他在去世前已经被疾病折磨很多年了。