情态动词(网友来稿)
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Ⅰ知识要点
情态动词本身有词义,但词义不完整,不能单独作谓语,需要在其后接动词原形构成复合谓语,情态动词没有人称和数的变化。
情态动词表示说话人对某一动作或状态的态度。情态动词主要表示能力、允许、必须、批评和推测。一个情态动词可能有多种用法。说话人的某一种态度可能用多个情态动词表示。几个情态动词表示说话人的态度,有时意义相同,有时却有区别,互相不能替代。本讲主要通过情态动词的用法比较掌握其区别。现分七个问题讲解。
一.表能力：(ability)
1. can 只表能力,be able to 表最终产生的能力
She can speak EngLish .
By the time she finishes her courses,shell be able to speak EngLish well .
2. can没有将来时和完成时,要用be able to 代替
She will be able to see you tomorrow .
I have not been able to go to work for three days .
3. could不能表过去实际发生的行为,只表示过去一般 的能力
was (were,had been)able to 则能。意思是 succeed in doing或manage to do
Could not =was not able to
When I was five ,I could already swim .
He could swim,but he didn t jump into the water to save the boy .(没有发生行为）
He couldnt(=wasnt able to )go to London yesterday .（否定式相同）
Some of us can use the computer now but we couldn￠t three years ago .
Einstein was able to leave Germany before the war began .
Although the driver was badly hurt ,he was able to explain what had happened .
(实际发生了行为）
二.表允许：(permission)
1. may ,can (might ,could)
You may (can)go now .=I permit you to go .
Can I have a word with you ?
Could you lend me your camera ?
2. 否定式
may not = must not =can not
注意重音：He may not go tomorrow .(表允许）
=I do not permit him to go tomorrow .
He may not go tomorrow .（表推测）
=It is possible that he will not go tomorrow .
You cannot (mustn t,may not )play football in the park on Sundays ,though you may do
so on weekdays .
You mustnt smoke here.
=You cannot smoke here.
=You may not smoke here.
=You are not allowed tosmoke here.Y
=You d better not smoke here
三.表必须
1. must 表主观上的必须
have to + 原形=have got to + 动词原词形表客观上的必须
I must finish this before I go . (主观）
As we missed the last bus ,we had to walk home .（客观）
You have got to do it today .
2. must没有过去时和将来时,可用have to 表主观
I had to go yesterday .
I shall have to go to my hometown some day .
I have had to go three times already .
但间接引语或有间接引语味道的句子里可用must表过去。
Yesterday morning I told my mother that I must call on a frierd at once .
3. 表暂时必要用must,经常的需要用have to
I must go shopping this morning .
Do you have to go shopping every day ?
I don t have to go to school on Sundays .
4. mustn t 和may not， cannot表示禁止某人做事同义。
You mustn t walk on the grass .(may not )
Cars mustn t be parked in front of the house .(cannot)
5. 表示道义上的必要用ought to
I feel I ought to help you .
There ought not to be much noise in a hospital .
四.表批评：
1.表示对现在动作的批评
should (nt) + ( be )doing (肯定形式表否定意思,否定形式表肯定意思)
You should be reviewing your lessons ,why are you palying chess here ?
She should not be working .She is still very weak .
2. 表示对过去动作的批评
Should (nt) + have done (肯定形式表否定意思,否定形式表肯定意思)
I should have answered your letter soorer,but I have been too busy recently .
You should have taken her home .
You ought to have done the work yesterday .
The child ought not to have been allowed to go alone .
五.表推测 (possibility)
1.表对现在事实的推测：
①表示对现在状态的推测
There must be some tea in the pot ,
She must know several foreign langrages .
The teacher may be in the Lab .
Who might the man be ?
This ought to be your notebook .
The worker cannot be over sixty.(否定式用cant)
Can the news be true ?(疑问式)
How could you be so carless ?
注：①might 不表过去,只表婉转,可能性比 may 小。
② ought to表推测,与must相近,must表强调。
(2).表示对现在动作的推测
They must (may)be waiting for us now .lets hurry up .
It must (may) be snowing outside .
She must (may) still be thinking about the questions you raised .
He cant be watching TV now .He must be reviewing his lessons in the library .
What can they be argurning about ?
2. 对过去事实的推测：
①表示从过去对过去的事实的推测：
He was afraid it might rain that evening .
He could be very excited when he heard some good news .
John said the professor must be at least seventy .
②表示从现在对过去事实的推测：
They must have gone home .
She may (might) have gone to hospital .
She cant (couldnt )have done such a thing. (否定式用cant和couldnt均可)
Where can (could)he have gone ?
Can (could)she have forgatten my address?
3. 表示对将来事实的推测：
It must come sooner or later .
=It surely come sooner or later .
He may come or may not ,I don t know .
- Can he be back before May Day ?
- Im afraid he cant (be back before May Day)
情态动词 + 某些动词(go ,leave )的进行时,表对将来的推测
She may be leaving tomorrow .
I might (may)be going back is the fall .(秋季)
六. need与dare
(一).need和dare用于实义动词的特点是：
1.与其他实义动词一样,有词形变化
The leaves of this plant are yellow because it needs water .
Who dares to go ?
He needed help when he was at college .
She dared to be left alone at home when she was a little girl .
2.构成否定式和疑问式用助动词do
It doesnt need to be explained again .
Does he need to repair the machine at once ?
He did not dare to climb that mountain .
Don t you dare to touch me ?!
3.need接动名词作宾语表被动,接不定式表主动
dare接不定式作宾语,肯定式常接带to的不定式,否定式和疑问式带to与不带to均可。
The young trees need watering (to be watered).(如果接不定式则用被动式表示被动)
We need to discuss the matter carefully .
He dares to ask me that .
I dont dare (to) ask the question again .
Do they dare(to)come ?
(二).need 和dare用作情态动的特点是：
1.与其他情态动词一样,用于各人称、没有词形变化
第三人称单数一般现在时,不加"s"。
I dont believe you need go to shanghai .
Need we hand in the composition today ,teacher ?
No ,you neednt ./ Yes ,you must .(不说need)
The little girl said that she dare not go to town alone .
"If you dare speak to me like that again ,Ill give you a good beating(wipping)"
said the mother .
2. need和dare用于情态动词一般不用于肯定句。need只用于否定句和疑问句,dare只用
于否定句,疑问句和条件句
need的否定式 need not 或 neednt, dare的否定式 dare not 或 darent
不说：I need repair my watch today . 而说： I need to repair my watch today .
不说：She dared speak to a stranger . 而说：She dared to speak to a stranger .
He wanted to come to face me ,but he darent .
You neednt run so fast ,little one !
3. need 和dare用于情态动词,后接不带 to的不定式
He neednt be answered for it . She dare not say what she has just seen .
4. need 和dare接不定式的完成式,可表示过去的时间。
You neednt have told them the secret .
The students darent have asked the teacher when they met .
(三)．need 和dare可用作名词
There is no need to start so early .
Mary tried to ride on a cow for a dare .
(四)．need 和dare构成固定短语
We must train more experts to meet the needs of the four modernizations .(满足)
We will give you aids if need be .(有必要的话)
We will take steps at once in case of need (必要时)
We have got a great quantity of daily needs( 日用品) in recent years .
How dare you (he )…?"竟敢""胆大妄为"
How dare you say I￠m unfair ?
How dare you steal apples from my garden!
I dare say, = I think it is likely , perhaps(我看…可能,大概…)
I dare say it will snow today .
I dare say your invention will greatly benifit the whole world .
I dare say sports and games can be of sreat value to people who work with their
brains most of the day .
I dare say you are thirsty after the game .
Itll rain tomorrow ,I dare say .
(五).didnt need to do 表示过去不必做的事,实际未发生动作。
neednt have done 表示做了不必要做的事,确实发生了。
I didnt need to get up early this morning .
So I stayed in bed until lunch time .
I neednt have got up early ,because I had no classes this morning .
You neednt have written such a long composition .
I didnt need to ring the bell ,because the door opened when I got to it .
You neednt have spent so much money ,now we havent got enough money to buy
the tickets.
She didnt need to read those thick books ,which saved him a lot of time .
You neednt have had your radio repaired ,you could have repaired it yourself .
七."情态动词 + 不定式的完成式"表示一个过去的概念。
1. must have done (对过去情况的推测）
2. may (might)have done (同上)
3. cant (couldnt )have done (对过去情况推测的否定式)
4. could have done .(过去有能力做到的事,由于某种原因没做到)
5. might have done (过去有可能做到的事,由于某种原因没做到)
6. should(not) have done (对过去动作的批评)
7. ought to have done (同上)
8. needt have done (做了过去没有必要做的事)
9. darent have done ( 过去不敢做某事)
He must have arrived in shijiazhuang yesterday .
He may have missed the train .
He might have gone home .
I cant have taken it home .
You should have given him more help .
The wall shouldnt have been painted blue .
You ought to have handed in your composition yesterday .
You neednt have said that .
I darent have asked him when he was born .
Ⅱ高考试题及练习题
1. I didnt see her in the meeting room this morning .
she ____ at the meeting .
A.mustnt have spoken B.shouldnt have spoken
C.neednt have spoken D.couldnt have spoken
2. Where is my pen ? I ____ it .
A.might lose B.would have lost C.should have lost D.must have lost
3. I didnt hear the phone .I ____ asleep .
A.must be B.must have been B.should be D.should have been
4. ____they ____ their work so soon ?
A.Can …have completed B.Must…have completed
C.Should…have completed D.Need…have completed
5. -I saw Ann in the library yesterday .
-You _____ her ；she is still aboad .
A.must not see B.cant have seen C.mustnt have seen D.couldnt see
6. The train has gone .You two ____ on time .
A.should come B.must have come
C.ought to have come D.shouldn t have come
7. The little boys eyes are red .He ______.
A.must cry B.may cry C.must be cried D.must have cried
8. ____ she have lost the watch ?
A.Can B.May C.Need D.Must
9. You ____ your radio .Ive brought one .
A.mustnt have brought B.neednt have brought
C.mustnt bring D.neednt to bring
10. ----Did your sister break that window ?
---- ____ .
A.She must do it B.She may have done it
C.She may do it D.She can do it
11. ---- ____ she have lost her way?
---- She might have .
A.Must B.May C.Could D.Should
12. The ground was wet this morning . It ____ last might .
A.might have been rained B.must be raining
C.must have been rained D.must have rained
13. I parked my car right here but now it s gone . It _____ .
A.may be stolen B.must be stolen
C.must have been stolen D.must have stolen
14. ----We should have walked to the station ；it was so near .
--- -Yes .A taxi ___ at all nesessary .
A.wasnt B.hadnt been C.wouldnt be D.wont be
15. He ___ you more help ,even though he was very busy .
A.might have given B.might give C.may have given D.may give
16. ----Look ,someone is coming, guess ____ .
----Jack．Hes always on time .
A.Who can it be B.Who it can be C.Who he can be D.Who can he be
17. There was plenty of time .She ______ .
A.mustnt have hurried B.neednt have hurried
C.must not hurry D.couldnt have hurry
18. The plant is dead .I ___ it more water .
A.will give B.would have given
B.must give D.should have given
19. You ought ___ to stay here .
A.to allow B.to be allowed C.be allowed D.allow
20. We ___ for her because she never came .
A.neednt wait B.shouldnt have waited
C.mustnt wait D.mustnt have waited
21. Jenny ____ have kept her word . I wonder why she changed her mind .
A.must B.should C.need D.would
22. We ___ last night ,but we went to the coucert instead .
A.must have studied B.might study
C.should have studied D.would study
23. Tom ought not to ___ me your secret ,but he meant no harm .
A.have told B.tell C.be telling D.having told
24. The cat ___ hibernate in winter .
A.does not need to B.needn t
C.doesnt have to D.A or B or C
25. Neither of them ___ the snake .
A.dares catch B.dares to catch
C.dare catch D.A or B or C
26. He ____ have come here yesterday ,but he didn￠t .
A. could B.should C.ought to D.A or B or C
27. ----May I borrow your bike ?
----No ,you ____ .
A.mustnt B.may not C.had better not D.A or B or C
28. He was a good swimmer ,so he ___ swim to the river bank when the boat sank .
A.could B.succeeded C.might D.was able to
29. I got up early that morning ,but I ___ so because I had no work to do .
A.mustnt have done B.didnt need to do
C.neednt have done D.cant have done
30. I ___ up early this morning ,so I stayed in bed until 9 oclock a.m .
A.neednt have got B.didnt need to get
C.shouldnt have got D.cant have got
31. What ___ I do for you ,madam ?
A.shall B.can C.may D.will
32. He ___ see a doctor before it is too late .
A.must B.must have to C.need D.need have to
33. -Could I borrow your dictionary ?
-Yes ,of course you ____ .
A.might B.could C.should D.can
34.---- ____ I stop here sir ?
---- ____ No .Go on to the next paragraph ,please .
A.Will B.May C.Would D.Ought
35. I wasn￠t sure whether I ___ offer to help or not .
A.should B.might C.would D.can
36. ---- ____ we finish all the exersises in class ?
---- Yes ,you ____ .
A.Shall；will B.Need；can C.Can；might D.Must；must
37. ----May I put my bike here ?
---- No ,you ____
A.neednt B.cant C.wouldnt D.arent able
38. I ___ go if I had the chance .
A.can B.may C.will D.would
39. You ___ walk for miles and miles among the hills without meeting anyone .
A must B.need C.may D.have to
40. Our teachers are at work .You ____ make so much noise .
A.won t B.mustn t C.would not D.needn t
41. Im afraid it ___ rain tonight .
A.can B.could C.may be D.might
42. Dont be worried .The news ____ be true .
A.should not B.mustnt C.neednt D.cant
43. You ___ do what you like this morning .
A.could B.can C.are able to D.can be able .
44. ---- Need I start from the beginning ?
---- Yes ,you _____ .
A.need B.do C.can D.must
45. I wouder how he _____ that to the teacher .
A.dare to say B.dare say C.not dare say D.dare say
46. Some warm-blooded animals _____ biberate.
A.need not B.does not need to
C.needn t to D.do not need
47. Somebody _____ here only this morning .
A.must be B.must have been
C.can be D.should have been
48. I ___ them ,but I wasn t able to
A.ought to have helped B.must have helped
C.might help D.needn t have helped
49. You are wet through .You ___ in the rain .
A.must come B.must have caught
C.may catch D.must have got caught
50. He worked hard ,and ____ pass his examinations .
A.could B.is able to C.can D.was able to
Ⅲ 练习答案
1-5 DDBAB 6-10 CDABB 11-15 CDCAA 16-20 BBDBB 21-25 BCADD
26-30 DDDCB 31-35 BADBB 36-40 DBDCB 41-45 DDBDD 46-50 ABADD
Ⅳ 练习题分析
1. couldnt have spoken是对过去情况推测的否定式,可改成cant have spoken , 其他三项
均不能表示推测。
2. must have lost it 是对过去情况推测的肯定式。must可换成may 或might,但可能性
小。must可能性最大。
3. must have been表示对过去情况的推测。 must可换成may 或might .
4. can…have completed表示对过去情况推测的疑问式, can可换成could ,但不能用must,
may 和might构成推测的疑问句。
5. cant have seen 是对过去情况推测的否定式,cant能被couldnt替换。mustnt have
seen 不能表示对过去情况的否定式。
6. ought to have come 是对过去的批评,肯定形式,否定意思,说明你们俩没赶上火车是因
为来晚了。这里的ought to 与 should 同意,可互相替代。
7. must have cried 是对过去情况推测的肯定式。根据是the boy￠s eyes are red 。must
可以改成may 或might 。
8. can she have lost …?是对过去情况推测的疑问句。can 可改成could , 但不能用must ,
may 或might 。
9. neednt have brought 表示过去没有必要做的事,实际做了,但没有带来负作用。根据是
I have brought one 。
10. "She may have done it ."是对过去情况的肯定式,表示可能性较小。D项的 can只用于
疑问句或否定句。A和C项是对将来动作的推测。
11. "Could she have lost …"表示对过去情况推测的疑问句, could可被can所替换,但不能
用Must或May 。
12. must have rained …是对过去情况推测的肯定式。根据是The grourd was wet this
morning 。
13. "must have been stolen"是对过去情况推测的肯定式。根据是I parked my car right
here but now its gone 。
14. "A taxi wasnt at all necessary ."中的谓语动选了过去时。根据是We should have
walked to the station。"should + have + 过去分词"这一结构表示一个过去的概念。
15. "might have given"表示过去有可能做到的事由于某种情况没做成。本题的意思是"既
使他很忙,他还是可以给予你更多的帮助,但实际上并没有做到,这是肯定形式,否定意
思。"
16. 本题的意思是"看,有人来了。猜一猜是谁?"guess之后的who 从句是宾语从句,故用陈
述句的句式。it是从句的主语,是人称代词。it用于人表示搞不清姓别。C项的主语是he
,显然不合实际情况。
17. "neednt + have + 过去分词"这一结构表示做了过去没有必要做的事。根据是There is
plenty of time 。但这并没有坏影响。neednt不能改成mustnt 和couldnt , 因为它们没
有这种功能。
18. should have given 是对过去的批评。树死了是因为我浇水不多。本题意思是我该给
树多浇水,实际并没有多浇水。肯定形式,否定意思。
19. ought to 是情态动词,应接原形动词,但由于allow一词与逻辑主语You成被动关系,故用
be allowed.这称为含有情态动词的被动语态.
20. Shouldnt have waited 表示对过去动作的批评,是婉转的批评,留有余地的批评。否定
形式,肯定意思。
21. Should have kept her word 表示对过去动作的批评,是婉转的批评,有余地的批评。形
式上肯定,意思上否定。
22. Should have studied 表示对过去动作的批评,用法同21题。
23. Tom ought not to have told me…是对过去动作的批评,ought not等于Shouldnt,用法同
20题。
24. 选项A.does not need to hibernate中的need是实义动词,因为does not帮助它构成否定
式;B项neednt hibernate 中的neednt是情态动词,因为其本身构成否定式;C项doesnt
have to hibernate,意为"没有必要…"和A、B两相同意。故三项全正确。
25. 选项A.dares catch中的dares为实义动词,应接带to的不定式作宾语,但由于句首的
Neither构成这句话的否定句。实义动词,dare在否定句中,不定式宾语可以省to;选项
B。dares to catch 中的dares是实义动词,可接带to 的不定式宾语;选项C。dare catch
中的dare为情态动词,其后只能接原形动词,用于否定式,疑问式或条件句。故三项全正
确。
26. 选项A . could have come … 表示过去有能力做到的事,由于其中原因没做成；选项
B。should have come是对过去动作的批评,是婉转的批评,留有余地的批评,肯定形式,
否定意思;选项C。ought to 等should ,用法同选项B。故三项在语法和意思上全成立。
27. 选项A. mustnt和B. may not 表示禁止某人做某事同意。此外,还可以用cant和had
better not 等。
28. could 和 was able to 都表示过去有能力做某事。但could只表示泛指能力,不表示实施
了一个动作。was (were)able to 才表示过去既有能力,也实施了一个动作。本题表示
他的确游到岸边。
29. neednt have done 表示过去没有必要做的事,实际做了,但无负作用。本题的意思是那
天早晨没有必要早起,因为不上班,但实际早起了。
30. didnt need to do sth 是过去没有必要做的事,实际也没有做。
31. What can I do for you 中的can 表示能力,这是服务行业对顾客的礼貌用语。在不同地
方,翻译也不同。在商店,译成"你买什么货?"。在书店,就是"你买什么书?"。这句话不
能用"what do you want ?"代替。
32. 选项A. must表示"必须",是主观上的"必须"。选项C. need ,用于肯定句,必须是实义动
词,宾语应是to see ,即带to 的不定式。need用于情态动词,只用于否定句或疑问句,不
能用于肯定句,故C项错。
33. 问句中的could 并非是过去式,而是表示委婉,客气的礼貌用语,但回答不能说yes ,you
could 。正确的答语有两种：Yes ,you can 或Yes ,you may。
34. May I stop here 中的May表示允许,还可以用can,但May较多用.但不能用其他各项。
35. might offer 是对将来的推测。must表示可能性最大,但也不是百分之百,may可能性小,
might可能性最小。这里用might的根据是I wasnt sure 和whether。其他各项均无此用
法。
35. might offer表示对将来动作的推测。情态动词must接原形动词,表示对将来的推测时
可能性最大,may表示可能性小,might最小。
36. must表"必须"用于疑问句时,其肯定回答是Yes ,you must,否定回答是No, you neednt;
need表"必要"用于疑问句,其肯定回答用Yes,you must,否定回答用 No,you neednt。
37. May表示允许用于疑问句时,其肯定回答是Yes,you may,否定回答有三种即No,you
may not;No,you mustnt;和No,you cant。还可以说No,you had better not。
38. 本句的would是情态动词用于虚拟语气,因为条件从句中用的是had,用过去时表示对现
在的虚拟。
39. may walk是情态动词接原形动词,表示对将来的推测,但是可能性比must较小,比might
较大些。must表示可能性较大,又与实际不相附。
40. mustnt make so much noise是不允许某人做某事,原因是Our teacher is at work。禁
止某人做某事还可用may not 和can not。不能用neednt。
41. might rain tonight是对将来的推测,表示可能较小用might,这是由Im afraid所决定的。
42. Cant be true表示对现在状况推测的否定式,其他三项均无此种用法。
43. can do what you like中的can不表能力,而表允许,和may的用法相同。
44. 由need构成的疑问句,其肯定回答是Yes,you must,否定回答是No,you needn t。
45. D为正确答案。dare一词既可以作情态动词,也可以作实义动词。作情态动词,后接原
形动词,作实义动词,后接带 to的不定式。dared say应发生在wonder之前,这就否定了A
和B项。全句的含义是"我不知道他怎么敢跟老师说那话。"
46. need一词既可作情态动词,也可作实义动词。作情态动词时,后接原形动词,没有人称
和数的变化。作实义动词时,后接带to的不定式作宾语。B项的数不对,C项多了to,D项
少to,故A为正确答案。
47. must have been here是对过去情况的推测,因为this morning为过去时间状语。
48. I ought to have helped them中的ought to 等于should,表示过去动作的批评。用ought
to表示道义上我应帮助他们,但由于某种原因没办成。
49. must have got canght中的got与been同义。be caught in the rain表示被雨淋,原因是
You are wet through。
50. could与was able to都能表示过去能力,但could只泛指有能力,不表示实际发生的行
为。而was able to 却能表示实际发生的行为,相当succeeded in doing。

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