Ⅰ知識要點
情態(tài)動詞本身有詞義,但詞義不完整,不能單獨作謂語,需要在其后接動詞原形構(gòu)成復合謂語,情態(tài)動詞沒有人稱和數(shù)的變化。
情態(tài)動詞表示說話人對某一動作或狀態(tài)的態(tài)度。情態(tài)動詞主要表示能力、允許、必須、批評和推測。一個情態(tài)動詞可能有多種用法。說話人的某一種態(tài)度可能用多個情態(tài)動詞表示。幾個情態(tài)動詞表示說話人的態(tài)度,有時意義相同,有時卻有區(qū)別,互相不能替代。本講主要通過情態(tài)動詞的用法比較掌握其區(qū)別�，F(xiàn)分七個問題講解。
一.表能力：(ability)
1. can 只表能力,be able to 表最終產(chǎn)生的能力
She can speak EngLish .
By the time she finishes her courses,shell be able to speak EngLish well .
2. can沒有將來時和完成時,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不能表過去實際發(fā)生的行為,只表示過去一般 的能力
was (were,had been)able to 則能。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 .(沒有發(fā)生行為）
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 .
(實際發(fā)生了行為）
二.表允許：(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 .(表允許）
=I do not permit him to go tomorrow .
He may not go tomorrow .（表推測）
=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.表必須
1. must 表主觀上的必須
have to + 原形=have got to + 動詞原詞形表客觀上的必須
I must finish this before I go . (主觀）
As we missed the last bus ,we had to walk home .（客觀）
You have got to do it today .
2. must沒有過去時和將來時,可用have to 表主觀
I had to go yesterday .
I shall have to go to my hometown some day .
I have had to go three times already .
但間接引語或有間接引語味道的句子里可用must表過去。
Yesterday morning I told my mother that I must call on a frierd at once .
3. 表暫時必要用must,經(jīng)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義。
You mustn t walk on the grass .(may not )
Cars mustn t be parked in front of the house .(cannot)
5. 表示道義上的必要用ought to
I feel I ought to help you .
There ought not to be much noise in a hospital .
四.表批評：
1.表示對現(xiàn)在動作的批評
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. 表示對過去動作的批評
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.表推測 (possibility)
1.表對現(xiàn)在事實的推測：
①表示對現(xiàn)在狀態(tài)的推測
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 ?(疑問式)
How could you be so carless ?
注：①might 不表過去,只表婉轉(zhuǎn),可能性比 may 小。
② ought to表推測,與must相近,must表強調(diào)。
(2).表示對現(xiàn)在動作的推測
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. 對過去事實的推測：
①表示從過去對過去的事實的推測：
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表示從現(xiàn)在對過去事實的推測：
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. 表示對將來事實的推測：
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)
情態(tài)動詞 + 某些動詞(go ,leave )的進行時,表對將來的推測
She may be leaving tomorrow .
I might (may)be going back is the fall .(秋季)
六. need與dare
(一).need和dare用于實義動詞的特點是：
1.與其他實義動詞一樣,有詞形變化
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.構(gòu)成否定式和疑問式用助動詞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接動名詞作賓語表被動,接不定式表主動
dare接不定式作賓語,肯定式常接帶to的不定式,否定式和疑問式帶to與不帶to均可。
The young trees need watering (to be watered).(如果接不定式則用被動式表示被動)
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用作情態(tài)動的特點是：
1.與其他情態(tài)動詞一樣,用于各人稱、沒有詞形變化
第三人稱單數(shù)一般現(xiàn)在時,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 .(不說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用于情態(tài)動詞一般不用于肯定句。need只用于否定句和疑問句,dare只用
于否定句,疑問句和條件句
need的否定式 need not 或 neednt, dare的否定式 dare not 或 darent
不說：I need repair my watch today . 而說： I need to repair my watch today .
不說：She dared speak to a stranger . 而說：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用于情態(tài)動詞,后接不帶 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,可表示過去的時間。
You neednt have told them the secret .
The students darent have asked the teacher when they met .
(三)．need 和dare可用作名詞
There is no need to start so early .
Mary tried to ride on a cow for a dare .
(四)．need 和dare構(gòu)成固定短語
We must train more experts to meet the needs of the four modernizations .(滿足)
We will give you aids if need be .(有必要的話)
We will take steps at once in case of need (必要時)
We have got a great quantity of daily needs( 日用品) in recent years .
How dare you (he )…?"竟敢""膽大妄為"
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 表示過去不必做的事,實際未發(fā)生動作。
neednt have done 表示做了不必要做的事,確實發(fā)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."情態(tài)動詞 + 不定式的完成式"表示一個過去的概念。
1. must have done (對過去情況的推測）
2. may (might)have done (同上)
3. cant (couldnt )have done (對過去情況推測的否定式)
4. could have done .(過去有能力做到的事,由于某種原因沒做到)
5. might have done (過去有可能做到的事,由于某種原因沒做到)
6. should(not) have done (對過去動作的批評)
7. ought to have done (同上)
8. needt have done (做了過去沒有必要做的事)
9. darent have done ( 過去不敢做某事)
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高考試題及練習題
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 …h(huán)ave completed B.Must…h(huán)ave completed
C.Should…h(huán)ave completed D.Need…h(huán)ave 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 練習答案
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 練習題分析
1. couldnt have spoken是對過去情況推測的否定式,可改成cant have spoken , 其他三項
均不能表示推測。
2. must have lost it 是對過去情況推測的肯定式。must可換成may 或might,但可能性
小。must可能性最大。
3. must have been表示對過去情況的推測。 must可換成may 或might .
4. can…h(huán)ave completed表示對過去情況推測的疑問式, can可換成could ,但不能用must,
may 和might構(gòu)成推測的疑問句。
5. cant have seen 是對過去情況推測的否定式,cant能被couldnt替換。mustnt have
seen 不能表示對過去情況的否定式。
6. ought to have come 是對過去的批評,肯定形式,否定意思,說明你們倆沒趕上火車是因
為來晚了。這里的ought to 與 should 同意,可互相替代。
7. must have cried 是對過去情況推測的肯定式。根據(jù)是the boy￠s eyes are red 。must
可以改成may 或might 。
8. can she have lost …?是對過去情況推測的疑問句。can 可改成could , 但不能用must ,
may 或might 。
9. neednt have brought 表示過去沒有必要做的事,實際做了,但沒有帶來負作用。根據(jù)是
I have brought one 。
10. "She may have done it ."是對過去情況的肯定式,表示可能性較小。D項的 can只用于
疑問句或否定句。A和C項是對將來動作的推測。
11. "Could she have lost …"表示對過去情況推測的疑問句, could可被can所替換,但不能
用Must或May 。
12. must have rained …是對過去情況推測的肯定式。根據(jù)是The grourd was wet this
morning 。
13. "must have been stolen"是對過去情況推測的肯定式。根據(jù)是I parked my car right
here but now its gone 。
14. "A taxi wasnt at all necessary ."中的謂語動選了過去時。根據(jù)是We should have
walked to the station。"should + have + 過去分詞"這一結(jié)構(gòu)表示一個過去的概念。
15. "might have given"表示過去有可能做到的事由于某種情況沒做成。本題的意思是"既
使他很忙,他還是可以給予你更多的幫助,但實際上并沒有做到,這是肯定形式,否定意
思。"
16. 本題的意思是"看,有人來了。猜一猜是誰?"guess之后的who 從句是賓語從句,故用陳
述句的句式。it是從句的主語,是人稱代詞。it用于人表示搞不清姓別。C項的主語是he
,顯然不合實際情況。
17. "neednt + have + 過去分詞"這一結(jié)構(gòu)表示做了過去沒有必要做的事。根據(jù)是There is
plenty of time 。但這并沒有壞影響。neednt不能改成mustnt 和couldnt , 因為它們沒
有這種功能。
18. should have given 是對過去的批評。樹死了是因為我澆水不多。本題意思是我該給
樹多澆水,實際并沒有多澆水�？隙ㄐ问�,否定意思。
19. ought to 是情態(tài)動詞,應接原形動詞,但由于allow一詞與邏輯主語You成被動關系,故用
be allowed.這稱為含有情態(tài)動詞的被動語態(tài).
20. Shouldnt have waited 表示對過去動作的批評,是婉轉(zhuǎn)的批評,留有余地的批評。否定
形式,肯定意思。
21. Should have kept her word 表示對過去動作的批評,是婉轉(zhuǎn)的批評,有余地的批評。形
式上肯定,意思上否定。
22. Should have studied 表示對過去動作的批評,用法同21題。
23. Tom ought not to have told me…是對過去動作的批評,ought not等于Shouldnt,用法同
20題。
24. 選項A.does not need to hibernate中的need是實義動詞,因為does not幫助它構(gòu)成否定
式;B項neednt hibernate 中的neednt是情態(tài)動詞,因為其本身構(gòu)成否定式;C項doesnt
have to hibernate,意為"沒有必要…"和A、B兩相同意。故三項全正確。
25. 選項A.dares catch中的dares為實義動詞,應接帶to的不定式作賓語,但由于句首的
Neither構(gòu)成這句話的否定句。實義動詞,dare在否定句中,不定式賓語可以省to;選項
B。dares to catch 中的dares是實義動詞,可接帶to 的不定式賓語;選項C。dare catch
中的dare為情態(tài)動詞,其后只能接原形動詞,用于否定式,疑問式或條件句。故三項全正
確。
26. 選項A . could have come … 表示過去有能力做到的事,由于其中原因沒做成；選項
B。should have come是對過去動作的批評,是婉轉(zhuǎn)的批評,留有余地的批評,肯定形式,
否定意思;選項C。ought to 等should ,用法同選項B。故三項在語法和意思上全成立。
27. 選項A. mustnt和B. may not 表示禁止某人做某事同意。此外,還可以用cant和had
better not 等。
28. could 和 was able to 都表示過去有能力做某事。但could只表示泛指能力,不表示實施
了一個動作。was (were)able to 才表示過去既有能力,也實施了一個動作。本題表示
他的確游到岸邊。
29. neednt have done 表示過去沒有必要做的事,實際做了,但無負作用。本題的意思是那
天早晨沒有必要早起,因為不上班,但實際早起了。
30. didnt need to do sth 是過去沒有必要做的事,實際也沒有做。
31. What can I do for you 中的can 表示能力,這是服務行業(yè)對顧客的禮貌用語。在不同地
方,翻譯也不同。在商店,譯成"你買什么貨?"。在書店,就是"你買什么書?"。這句話不
能用"what do you want ?"代替。
32. 選項A. must表示"必須",是主觀上的"必須"。選項C. need ,用于肯定句,必須是實義動
詞,賓語應是to see ,即帶to 的不定式。need用于情態(tài)動詞,只用于否定句或疑問句,不
能用于肯定句,故C項錯。
33. 問句中的could 并非是過去式,而是表示委婉,客氣的禮貌用語,但回答不能說yes ,you
could 。正確的答語有兩種：Yes ,you can 或Yes ,you may。
34. May I stop here 中的May表示允許,還可以用can,但May較多用.但不能用其他各項。
35. might offer 是對將來的推測。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。這里用might的根據(jù)是I wasnt sure 和whether。其他各項均無此用
法。
35. might offer表示對將來動作的推測。情態(tài)動詞must接原形動詞,表示對將來的推測時
可能性最大,may表示可能性小,might最小。
36. must表"必須"用于疑問句時,其肯定回答是Yes ,you must,否定回答是No, you neednt;
need表"必要"用于疑問句,其肯定回答用Yes,you must,否定回答用 No,you neednt。
37. May表示允許用于疑問句時,其肯定回答是Yes,you may,否定回答有三種即No,you
may not;No,you mustnt;和No,you cant。還可以說No,you had better not。
38. 本句的would是情態(tài)動詞用于虛擬語氣,因為條件從句中用的是had,用過去時表示對現(xiàn)
在的虛擬。
39. may walk是情態(tài)動詞接原形動詞,表示對將來的推測,但是可能性比must較小,比might
較大些。must表示可能性較大,又與實際不相附。
40. mustnt make so much noise是不允許某人做某事,原因是Our teacher is at work。禁
止某人做某事還可用may not 和can not。不能用neednt。
41. might rain tonight是對將來的推測,表示可能較小用might,這是由Im afraid所決定的。
42. Cant be true表示對現(xiàn)在狀況推測的否定式,其他三項均無此種用法。
43. can do what you like中的can不表能力,而表允許,和may的用法相同。
44. 由need構(gòu)成的疑問句,其肯定回答是Yes,you must,否定回答是No,you needn t。
45. D為正確答案。dare一詞既可以作情態(tài)動詞,也可以作實義動詞。作情態(tài)動詞,后接原
形動詞,作實義動詞,后接帶 to的不定式。dared say應發(fā)生在wonder之前,這就否定了A
和B項。全句的含義是"我不知道他怎么敢跟老師說那話。"
46. need一詞既可作情態(tài)動詞,也可作實義動詞。作情態(tài)動詞時,后接原形動詞,沒有人稱
和數(shù)的變化。作實義動詞時,后接帶to的不定式作賓語。B項的數(shù)不對,C項多了to,D項
少to,故A為正確答案。
47. must have been here是對過去情況的推測,因為this morning為過去時間狀語。
48. I ought to have helped them中的ought to 等于should,表示過去動作的批評。用ought
to表示道義上我應幫助他們,但由于某種原因沒辦成。
49. must have got canght中的got與been同義。be caught in the rain表示被雨淋,原因是
You are wet through。
50. could與was able to都能表示過去能力,但could只泛指有能力,不表示實際發(fā)生的行
為。而was able to 卻能表示實際發(fā)生的行為,相當succeeded in doing。