2018年高考英語備戰必備秘籍之情態動詞和虛擬語氣易錯起源
【易錯雷區，步步為贏】
1.My room is a mess, but I __________clean it before I go out tonight. I can do it in the morning.
A. daren’t B. shouldn’t C. needn’t D. mustn’t
【答案】C
【解析】 句意：我的房間很亂，但是在今晚我出去之前不需要打掃，我可以明天早晨再打掃。A.不敢；B.不應該；C不需要；D.不許。根據句意，故選C。
2. _________ not for the support of the teachers, the student could not overcome her difficulty.
A. It were B. Were it C. It was D. Was it
【答案】B
【解析】考查虛擬語氣的省略。虛擬語氣中，be動詞統一用were；虛擬語氣的省略形式主要是把if省略，同時把were/should/had提前，即Were /Should/ Had I...，故選B。
3. _______ not for the support of the teachers, the student could not overcome her difficulty.
A. It were B. Were it C. It was D. Was it
【答案】B
4.If the new safety system _______ to use, the accident would never have happened.
A. had been put B. were put C. should be put D. would be put
【答案】A
【解析】句意：如果這個新的安全系統被投入使用過的話，這個事故就不會發生了。根據主句確定是對過去情況的虛擬，所以從句謂語用had done形式，此外根據句意可知是被動，用被動語態，故A項是正確的。
5.________(have)the governments and scientists not worked together，AIDSrelated deaths would not have fallen since their highest in 2005.
【答案】Had 【解析】句意：如果政府和科學家不共同努力，與艾滋病相關的死亡就不會從2005年的最高點下降。這是一個省略了從屬連詞if的虛擬語氣句，使用了倒裝句式。根據主句的would not have fallen可知，這裡是表示過去的虛擬語氣，所以用had。
6.George can't ________(go)too far.His coffee is still warm.
【答案】have gone 【解析】句意：喬治不可能走得太遠了。他的咖啡仍然是溫的。can't have done是對過去的否定推測。
7. This does not mean that we have to write or call our friends every day.It does mean，however，that we care enough about our friends to find out how they are doing from time to time.
【解析】考查情態動詞。根據語境特別是前面的have to可知，此處需要一個情態動詞，should應該，語氣合適；如用must，語氣太強；may/can語氣太弱。
【答案】should
8. I was really happy to be writing a detective story.But after the first few pages，I just _____write any more.
【解析】考查情態動詞。寫了幾頁之後，我就再也寫不出來了。此處表達過去的能力。
【答案】couldn't
9. I'm Captain John Blanchard.You _____be Miss Hollis.I am glad to meet you here.
【解析】考查情態動詞。你一定是Hollis女士。根據語境可知此處要用must表示肯定推測。
【答案】must
10. He walked in as if he ___(buy) the school，and the word quickly got around that he was from New York City.
【解析】考查虛擬語氣。在人稱代詞he後，顯然是作謂語；又因他不可能是買下了這個學校，故應用虛擬語氣，與過去事實相反，故填had bought。
【答案】had bought
11. I recommend that you _____(try) Baihe.com.
【解析】考查虛擬語氣。recommend, suggest, request, command等後面的賓語從句使用虛擬語氣，即should ＋動詞原形，should可省略。
【答案】(should) try
12. Tom：Sandy.It seems that only half of the students passed the final exam.
Sandy：Really? The exam _____ have been very difficult this time.
【解析】考查情態動詞。答句意為“這次的考試一定很難”。must have done肯定……，表示對過去的肯定猜測。
【答案】must
13. It's a pity you were late，otherwise you ______(see) the film star Rain from Korea.
【解析】考查虛擬語氣。根據otherwise判斷此處是含蓄型的虛擬語氣，表示對過去的虛擬時，主句用would have done。
【答案】would have seen
14. Had the government limited the sales of cars much earlier，traffic jam and pollution ___not be so serious now.
【解析】考查虛擬語氣。句尾有now，即主句是對現在的虛擬，應該使用would ＋動詞原形。
【答案】would
15. If you will stay here longer，you may.But you ______ leave before this weekend.
【解析】考查情態動詞。根據but可知，此處強調說話人主觀上認為“必須”做某事，要求對方必須在週末前離開。must必須。
【答案】must
【名師點睛，易錯起源】
易錯起源1、情態動詞的詞彙義辨析
例1．I have worried before I came to the new school, for my classmates here are very friendly to me.
【解析】句意：在來到新學校前我本不必擔心，因為在新學校我的同班同學對我很友好。考查情態動詞。needn't have done...本不必做的事做了。
【答案】needn't
【名師點睛】情態動詞的基本用法
I.can(could)
1.表示體力或腦力方面的能力，或根據客觀規定律能做某事的能力，意思是“能夠”。can表“能夠” 時，既可指將來，也可指現在。be able to 在表示能力時與can同義，但可用:於各種時態，強調通過努力克服困難成功地做某事，相當managed to do 或succeeded in doing.例如:No one can (is able to) finish such a difficult thing.
He can speak English.
I can go there now.
With the help of the fire men ,the the trapped peopel was able to leave the burning buildung(不能用could)
2.表示許可、允許，在疑問句中表示 “請求，許可”，否定句中表示 “不許”，此時可與may通採用，有時cannot可以表示 “禁止”，相當於“mustn’t”,例如:
May(Can)I help you?
That sort of thing can’t go on !
You can’t ( mustn’t, are not allowed to ) play computer games again.
3.表示推測，強調客觀可能性“可能、會”，can多用於疑問句和否定句，表示猜測時，情態動詞後可用進行式或完成式。
—There comes a man. Who can it be?
—It must be our English teacher.
—No, it can’t be him. He has gone to America!
He can’t have gone there alone.
4.could表示“能力”“可能性”“許可”，為can的過去式。一般用於委婉、客氣地提出問題或陳述看法，此時can，could並沒有時間上的差別，只是 could的語氣更客氣些。回答時用原形回答。
—Could I borrow your English dictionary?
—Of course you can. Go ahead.
Ⅱ.may,might( might 為 may 的過去式)
1.表示許可，有“可以”的意思，詢問或說的一件事可不可以做，有時可以用can互換。其否定式 may not表示“不可以、禁止、阻止”等，常用must not =mustn’t代替，may用於疑問句中，回答這種問題時，多避免用may，而用其他形式，以免顯得口氣太嚴峻或不客氣。例如:
—Mum, may I go to the cinema tonight?
—Yes, you may. (No, you mustn’t/ you’d better not. ) 比較:—Yes, please/please don’t.
2.表推測、或許、可能的意思，表示一件事或許會發生，只用在陳述包中。
例如:Her parents may come to see her tomorrow.
3.may句式用來表示祝願。例如:
May you succeed! = I hope you may succeed.
May you be happy, healthy and wealthy!
4.might是may的過去式，表示可以做的事或可能發生的事；主句謂語動詞是過去時態時用 might不用may。might一般用於比may的口氣委婉，或表示現實的可能性更小一些的語境中.例如:
Our teacher suggested a few books which I might buy.
I wonder if I might buy some sugar now.
Ⅲ.must
1.表示必須要做的事，意為“必須”，否定式 mustn’t表示“不應該，不許可，禁止”等。因此，在回答帶有must的問句時，不用mustn’t，而用 needn’t或don’have to.例如:
—Must I hand in the paper now?
——Yes,you must.
—No,you needn’t./you don’t have to.
2.must在表示“必須”時與have to相近，have to比較強調客觀的需要，must著重主觀看法。另外 must不像have to那樣能有更多的時態。例如:
Tom, you must stay at home. (命令或叮囑)
I have to stay at home to look after my baby. (客觀需要)
3.表推測，暗含很大的可能性，意為“一定”只用於“肯定句”中。例如:
I think there must be a mistake.
4.偏偏、硬要、幹嘛(指做令人不快的事)。例如:
Hey, beys Must you shout so loudly?
Ⅳ.Shall
1.用於二、三人稱陳述句中。表示說話人給對方的命令、許諾、警告、強制、威脅、決心等。在疑問句中，表示徵詢聽話人是否願意。例如:
You shall have my answer tomorrow. (允許)
He shall be sorry for it one day, I tell you. (警告)
You shall do as I tell you. (命令或分咐)
Shall you go with me? (徵詢意見)
2.用於一、三人稱的疑問句中，表示說話人徵求對方的意見和向對方請示。例如:
Shall we begin our class?
When shall my father be able to leave hospital?
V. should 和 ought to
should表示勸告、建議常作“應當”講，與ought to有時可互換，ought to更注重一些責任義務。 should表示預測可能性，並譯作“可能，(按道理)應該”；而ought to則表示非常可能。Should用於委婉、謙遜地提出意見或建議，ousht to可表示因責任、義務等該做的事。例如:
We should (ought to) help each other in work.( ought to 的語氣要強)
They should come here now. (按道理應該到了)
I am your teacher, I ought to help with your study.(表示有這個責任)
Ⅵ.will和would
will可以表示意願、意志和決心，適用於各種人稱。可以用來表示各種傾向或習慣動作。有時還用來表示“難免”。其過去式是would，也可以是單獨的情態動詞，在表示委婉提出請求、建議或看法時，語氣比will委婉，肯定的回答時用will。例如:
Don’t worry. He will do his best.
Where there is a will, there will be a success.(表示習慣)
Accident will happen. ( 難免 )
Would you please do me a favor?
易錯起源2、情態動詞對話情景中的用法
例2．—Sorry, Mum! I failed the job interview again.
—Oh, it's too bad.You have made full preparations.
【答案】should
【名師點睛】
情態動詞中三組表達方式的用法區別
1.would與used to的區別。
在表示過去重複的習慣時，used to可用Would代替。used to強調過去的行為同現在的對比，含有“過去怎樣，而現在卻不這樣了”的含義；而Would則單純表示過去的習慣動作，常與often，everyday連用，當只是表示過去的狀態時，只能用used to.例如:
They would have a drind in the bar at noon.
Thy used to have a drink in the bar at noon.(現在右能不了)
China is not what it used to be.(表示對比，不能用would)
Every evening,she would sit in frnt of the door to wait for her son .(表示過去的習慣動作，不能用used to)
They used to be a temple on the to of the mountain.(表示過去的狀態，不能用would)
2.表示“寧願做某事”時，有下列句式結構:
would rather do something
would do sth. rather than do sth.
Would rather sb. did sth.
prefer to do sth.
Prefer to do sth. Rather than do sth.
prefer to do sth. to doing sth.
【錦囊妙計，戰勝自我】
情態動詞否定式所表達的含義
may not,might not 或許不，可能不
can’t can not(= be not able to)不能說
can’t,can not 不可能
may not,can’t, can not, mustn’t (= be not allowed to)不許可
need’t(= don’t have to)不必
shouldn’t,oughtn’t to (= be not supposed to)不應該
易錯起源3、情態動詞+have
例3．You be Carol.You haven't changed a bit after all these years.
【解析】句意：你一定是Carol，這些年以來你一點都沒變。must一定，表示推測，符合句意。
【答案】must
【名師點睛】
“情態動詞 +過去分詞”用法
1.must have done表示對過去已經發生的行為進行推測，意思是“想必、準是、一定做了某事”。例如:
It must have rained last night, for the ground was quite muddy.
The lights were out. They must have been asleep.
2.may／might have done表示對過去已經發生行為韻推測；意思是“也許；或許、已經(沒有)…”。
一般只用於肯定句或否定句中，不用於疑問句。用 might 表示語氣更加不肯定。例如:
It’s too late. I think he may have gone to bed.
He may not have finished the work. She might have caught a cold.
3.might have done表示“本來可能；…”，但實際上沒有發生的事情。還可以表示“本來應該或可以做某事”的意思；有輕微的責備語氣。例如:
You should not have swum in that river. You might have been eaten by fish.
You might have given him more help, though you were busy.
4.could have done用於肯定句中，表示“可能已經……”的意義，也可以表示過去沒有實現的可能性，意思為“本來可以……”。例如:
You could have done better, but you were too careless.
I went to New York last summer and stayed at a hotel, but I could have stayed with my brother.
I saw his father just now. He couldn’t have gone to Shanghai.
5.should／ougt to have done用於肯定句時，表示本該做某事，但實際上沒做；用於否定句時，則表示不該做的事反而做了。例如:
You should/ ought to have come to the meeting earlier.
He ought not to have treated his parents like that.
6.needn’t have done表示本來不必去做的事但做了。但是didn’t need to表示”沒有必要做而實際上也沒有做”。
例如:
You needn’t have taken a taxi here, for it was very near to my house.
I didn’t need to clean the room. My mother did it.
【錦囊妙計，戰勝自我】
can…have done和can not have done表示對過去發生的行為的懷疑和不肯定。
例如:
He cannot have taken away the magazine.
Can he have gone home?
易錯起源4、虛擬語氣的一些特殊句式
例4． If I (see)it with my own eyes, I wouldn't have believed it.
【答案】hadn't seen
【名師點睛】
虛擬語氣中的幾種特殊情況
1.if省略句
在條件句中，可省略if把were，had，should提到句首，變為倒裝句式。如果謂語動詞是否定形式時，不能用動詞的縮略形式。例如:
Should it (If it should) rain tomorrow; we would not go fishing.
Were it not (if it were not)the expense, I would go abroad now. (不能用 weren’t)
2.在would rather後的賓語從句中的虛擬語氣形式用動詞的過去式，在It is(hish) time (that)…句型中，從句中的謂語動詞用過去式，或 should + 動詞原形，但should不能省略。例如:
It is high time that you went to school.
It is high time we should start out.
I would rather they didn’t hear of the news.
3.在口語中，虛擬語氣的省略情況
口語中，虛擬語氣的省略情況要注意。如果是一般過去時，只保留did，could，were等助動詞、情態動詞或系動詞如果是過去完成時，要保留had；如果是過去將來時，要保留would／might.同時還要注意被動情況。例如:
①—Have you found the answer to the question?
—I wish I had( found the answer to the question).
②I can’t go to Beijing with you, but I wish I would (go to Beijing with you).
③—Have you finished your homework?
—I would have ( finished my homework) if I had not gone to the cinema last night.
④—The liitle boy who dark the poison by mistake died if he had been sent to the hospital earlier.
—Well. he should have been (sent to the hospital earlier).
【錦囊妙計，戰勝自我】
if only和 only if 句型
(1)if only可以用來表示對現在或未來的願望,也可以表示與過去事實相反的願望。例如:
If only I could swim.(現在的願望)
If only they would tell me what they have decided. (將來的願望)
If only they had remembered to buy some fruit just now. (與過去事實相反的願望)
(2)only if用於句首，後接從句主謂倒裝，意思是“只要，只有”。例如:
Only if the red light comes on is there any danger to employees.
Only if a teacher has given permissionis a student allowed to enter this room.
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