内容正文:
can
can’t
could
couldn’t
Tom _______ swim when he was born,
couldn’t
can
can’t
could
couldn’t
Tom couldn’t swim when he was born,
but he _____ swim really fast now.
can
情态动词
情态动词概述
情态动词本身具有一定词义,主要用来表明说话者对某一行为的态度和观点,包括能力、可能、命令、要求、许诺、威胁等。情态动词不能在句中单独作谓语。
情态动词的语法特征:
情态动词没有人称和数的变化。
情态动词必须在其后加动词原形一起构成谓语。
情态动词的否定形式:情态动词+not。
情态动词的一般疑问句:情态动词+主语+谓语动词(+其他)?
could、should、might、would本身为情态动词,表达更加委婉的语气,又可以作can、shall、may、will的过去式。除了could、should、might、would之外,其他情态动词本身并没有时态的变化。
4
目录
一、常用情态动词的用法
二、“情态动词+完成式”的用法
一、常用情态动词的用法
1 . can的用法
2. could的用法
(1)表示一般的能力。
(2)表示推测,意为“可能”,常用于否定句或疑问句中。
(3)表示“允许或请求(做某事)”,与may的意思差不多,常用于口语中。
(4)表示“有时会”,此时表示偶尔发生的情况。
(1)表示过去的能力。
(2)表示“可能性”,既可以表示过去的可能性,也可以表示现在的可能性,比can的可能性要弱。
Jim isn't very good at maths or science,but he can speak English very well. (一般的能力)
吉姆并不是很擅长数学和科学,但他的英语说得很好。
When I left school at 10, I couldn't read or write. (过去的能力)
我10岁离开学校时既不识字也不会写字。
That can't be Mary—she's in hospital.(可能)
那不可能是玛丽——她现在在住院。
3 . may的用法
4 . might的用法
(1)用来表示许可或征求对方的意见。
(2)表示“可能性”,比can表示的可能性小。
( 3 ) 表 示 祝 愿
(1)表示许可,尤指过去的许可。
(2)表示“可能性”,既可以指过去的可能性,也可指现在的可能性,指现在的可能性时比may的可能性小。
可能性:
can>could>may>might
May I use your phone? (征求意见)
我可以用你的电话吗?
He asked if he might go home. (过去的许可)
他问他是否能回家。
He might say that now,but he can soon change his mind.(可能性)
他现在也许会那么说,但他很快就会改变主意。
5 . must的用法
(1)表示“必须,一定要”,多指现在或将来的情况,强调说话人的主观语气。其否定形式是mustn't,意 为“一定不要,不允许,禁止”。
You must finish your homework before 10 o'clock.
你必须10点前完成家庭作业。
(2)表示推测,意为“一定是,准是”,常指有根据的、比较有把握的推测。这种用法只能用于肯定句中。
She is wearing a long face. She must be angry.
她脸拉得很长。她肯定是生气了。
(3)must问句的答语。
肯定回答:Yes,主语+must.
否定回答:No,主语+needn't./No,主语+don'/doesn't have to.
(4)must与have to的区别。
must意为“必须”,强调说话人的主观意志, 一般用于现在时。have to意为“不得不,必须”,强调客观需要,有多种时态。
We have to obey the school regulations. (客观需求)
我们必须遵守校规。
例1.—Hurry up, Jeff.Let's cross the road as quickly as possible.
—No,you .Don't you see the light is still red?
A.couldn't B.wouldn't C.mustn't D.needn't
例7. — I take your order, please?
—Yes,I'd like a steak.
A.Should B.May
C.Must D.Will
C
典例精析
B
can
can’t
could
couldn’t
I see some clouds. It _____ rain later.
Shall
May
Would
Need
you get me some paper, please?
6 . should/ought to的用法
7 . shall的用法
(1)表示理应或应该做的事,意为“应该,应当”。
(2)表示说话者根据一定的依据进行推测,意为“应该是,会是”。
(3)should可以表示说话人的惊奇、愤怒、失望等情感。
(1)表示征求对方的意见,常用于第一人称的疑问句中。
(2)常用于第二人称和第三人称的陈述句中,表示说话人给对方的许诺、命令、警告、威胁等。
I should exercise more.
我应该多锻炼。
He is honest,so what he said ought to be true.
他很诚实,因此他的话应该是真的。
Shall we start the meeting now?
我们现在可以开始开会了吗?
You shall get what you want if you behave well.
如果你表现好的话,你就会得到你想要的东西。
8 . will/would的用法
(1)表示意愿或允诺,would用于过去的情况。
She said she would try her best to help me.
她说她愿意尽她最大的努力来帮我。
(2)表示请求或要求,常用于第二人称疑问句中。would比will更客气、委婉。
Will you join in our discussion?
您愿意加入我们的讨论吗?
(3)表示习惯或特性。will用于现在时;would用于过去时,带有主观性,常意为“总是”。
Mom would tell us stories before we went to bed.
过去妈妈总会在我们上床睡觉前给我们讲故事。
9 . need的用法
10 . dare的用法
(1)在肯定句中,表示“需要”;在否定句中,表示“不必”。
(2)need问句的答语。
肯定:Yes,主语+must.
否定:No,主语+needn't.或者
No,主语+don't/doesn't have to.
(1)作情态动词时,意为“敢”,主要用于疑问句、否定句和条件状语从句中。
(2)dare也可作实义动词,其后跟不定式,有人称、数和时态的变化。在否定句和疑问句中,不定式符号to可以省略。
I need make a phone call.
我需要打个电话。
You needn't do all the housework.
你不必把所有的家务都干了。
—Need you help him?— 你需要帮助他吗?
—Yes,I must.(肯定回答)
—No,I needn't. 或 No,I don't have to. (否定回答)
If you dare speak to me like that again, you will be sorry.(条件)
如果你再敢那样对我说话,你会后悔的。
11. had better/would rather的用法
had better意为“最好”; would rather意为“宁愿”。
基本用法:
(1)后均接动词原形
(2)缩写形式:had better='d better;would rather='d rather
(3)否定形式:均在动词原形前加not
had better not do sth. 最好不要做某事
You'd better not go out after 10 o'clock.
would rather not do sth. 宁愿不做某事
He'd rather walk to school.
你最好不要晚上十点后出去。
他宁愿步行去学校。
12. used to的用法
表示过去的习惯动作或状态,强调现在已不存在,意为“过去常常”。
(1)后接动词原形
He used to play football.
他过去经常踢足球。
(2)在疑问句、否定句中,均有两种形式:
①疑问句
Did you use to live with your parents?
Used you to live with your parents?
你过去和父母住在一起吗?
②否定句
Mary usedn't to be a hardworking student.
Mary didn't use to be a hardworking student.
玛丽以前不是一个勤奋的学生。
注意:
used to do sth.过去常常做某事
be used to do sth.被用来做某事
be/get used to doing sth.习惯于做某事
例2. You go before your mother comes back.
A.have better not B.have better no
C.had better not D.had better no
例.4 Look!The light is on and Mother be in.
A.might B.may
C.must D.could
例.6 you like some tea now?
A.Could B.Would C.Might D.Should
C
典例精析
B
C
would you like . … 表 示 委 婉 地 提 出 请 求 、 建 议 等
我饿了,我可以吃一个汉堡吗?
I am hungry, can I have a hamburger?
他过去会开车。
He could drive a car in the past.
你能帮我学英语吗?
Could you help me with English?
1.表示对过去情况的推测。
(1)肯定推测:must have done一定(已经) …… (把握较大);
can/could/may/might have done可能(已经) …… (把握较小)
The children are playing in the garden.They must have finished their
homework.
孩子们正在花园里玩。他们一定已经完成了家庭作业。
My parents may have arrived in Canada.
我父母可能已经到加拿大了。
二、“情态动词+完成式”的用法
(2)否定推测:can't/couldn't have done 不可能(把握较大);
may/might not have done 可能不(把握较小)
The door was locked.He could not have been at home.
门锁着,他不可能在家。
The door was locked.He may/might not have been at home.
门锁着,他可能不在家。
(3)疑问推测:Can/Could ….have done.. ……可能已经 ……
My wallet isn't in my handbag. Can it have been lost?
我的钱包不在手提包里。是不是已经丢了?
2.表示对过去的虚拟。
(1)could have done
意为“本可以做某事(实际上未做)”
He could have been more careful.
他本可以更细心的。
(2)might have done
意为“本可能做某事(实际上未做)”
You might have given him more help,though you were busy.
虽然你很忙,但你本可能给他更多的帮助的。
(3)would have done
意为“本来会做某事(实际上未做)”
I would have gone to the hospital,but I felt much better.
我本来会去医院,但我感觉舒服多了。
(4)needn't have done
意为“本不需要做某事(实际上做了)"
You needn't have taken a taxi here,for it is very near to your house.
你本不必乘出租车来这儿的,因为这儿离你家很近。
(5)should/ought to have done
意为“本该做某事(实际上未做)”;
shouldn't/ought not to have done
意为 “本不该做某事(实际上做了)”
总结:
could have done
might have done
would have done
needn't have done
should/ought to have done
“本可以做某事(实际上未做)”
“本可能做某事(实际上未做)”
“本来会做某事(实际上未做)”
“本不需要做某事(实际上做了)’’
“本该做某事(实际上未做)”
You should/ought to have come to the meeting earlier.
你本该早点儿来开会的。
You shouldn't/ought not to have told her the truth.
你本不应该告诉她真相的。
典例精析
例.3 Mary earlier.The train left a minute ago.
A.should have come B.may come C.have come D.would come
A
例5.—Who's the boy standing at the school gate?
—It _ be John.He has gone to Dalian.
A.may B.mustn't C.won't D.can't
—Hurry up, Jeff.Let's cross the road as quickly as possible.
—No,you .Don't you see the light is still red?
A.couldn't B.wouldn't C.mustn't D.needn't
D
C
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