情態(tài)動詞和虛擬語氣
【2012年高考命題預(yù)測】
作為歷年高考必考語法點(diǎn)情態(tài)動詞依舊會是2012年高考的熱點(diǎn)。同學(xué)們首先應(yīng)該著重掌握情態(tài)動詞的基本用法，同時結(jié)合情態(tài)動詞的用法學(xué)習(xí)虛擬語氣。
【概述】情態(tài)動詞也叫語氣動詞，有一定的詞義，但本身不表示行為或狀態(tài)，而只是表示說話人對所說動作的看法，認(rèn)為它“可能”、“應(yīng)當(dāng)”、“必要”等。情態(tài)動詞不能單獨(dú)作謂語動詞，只能和動詞原形一起構(gòu)成謂語動詞。英語里的情態(tài)動詞主要有：can(could), may(might), must, shall, will, would, need, dare, should, ought to。情態(tài)動詞在任何主語后沒有人稱和數(shù)的變化。除must, need, ought to外，其他情態(tài)動詞有表示過去時的形式變化：
現(xiàn)在式 過去式
can could
may might
shall should
will would
dare dared
【重難點(diǎn)突破】
一、情態(tài)動詞
⒈ can 和could
⑴表示能力
can 表示現(xiàn)在或未來的能力，could作為can的過去式，表示過去的“能力”
Whales cannot live on land. 鯨不能生活在陸地上。
Before liberation few workers could support their families.
解放前幾乎沒有工人能養(yǎng)得起家。
* be able to 與can、could的異同：
◆be able to 可用于多種時態(tài)，can和could只用于現(xiàn)在時和過去時。
He will be able to go wi th us this afternoon.
他今天下午能和我們一起去。 （一般將來時）
I haven’t been able to see the difference yet.
我還不能看出區(qū)別在哪。（現(xiàn)在完成時）
He thought I would be able to do the work well.
他認(rèn)為我能把這項(xiàng)工作做好。（過去將來時）
The sick man was soon able to stand up.
病人很快能站立起來。（一般過去時）
◆如果表示過去“能夠”、“做到”，“設(shè)法干成了某事”，常用was/were able to …來表達(dá)（相當(dāng)于managed to do sth.或succeeded in doing sth.）,而不用could。
We were able to get there before the meeting began.
會前我們終于趕到那里。
◆can間或可用于肯定句，表示理論上的可能性，表示籠統(tǒng)的時間，事物的特征
Anybody who wants to try can be successful.
只要想試，任何人都可能成功。
Scotland can be very warm in September. 九月份蘇格蘭會很暖和。
（2）、表示許可和請求
在日常生活中，can可以代替may,表示“允許”；could 可以代替can用來表示現(xiàn)在時間的動作，但語氣較為婉轉(zhuǎn)，表請求。
☆Can/Could I use your pen?
我可以用一下你的鋼筆嗎？（表請求）(could 比can更客氣，語氣更委婉)
Yes, you can.( 回答時不能說成could)
（3）、習(xí)慣短語：
cannot…too… 越…越好
cannot but 不得不
You cannot be too careful. 你越仔細(xì)越好。
I cannot but do so. 我不得不這樣做。
（4）、can 和could 后面接動詞的完成式，表示對過去情況的猜測或判斷。can常用于疑問句和否定句，而could能用于肯定句，表示一個非事實(shí)的或不可能實(shí)現(xiàn)的可能性。
You were stupid to go skiing there. You could have broken your leg.
去那里滑雪你真是太傻了，你會摔斷腿的。（實(shí)際上沒有摔斷腿）
⑸could have done本來能做而實(shí)際未做，表達(dá)遺憾的感情色彩
----I stayed at a hotel while in New York.
----Oh, did you? You could have stayed with Jane.
在紐約期間，我無處安身，只好住在旅館里。
嗷，是嗎？你本可以和珍妮住在一起。（表達(dá)遺憾的感情色彩）
⒉ may 和might
⑴表示“允許”或“請求對方的允許”，might 比may 語氣更客氣、更委婉
May/Might I take the book out of the room?
我可以把這本書拿出房間嗎？（表請求允許）(might 比may更委婉，更客氣)
⑵表示“可能性”
常用于肯定句和否定句，指說話人的猜測，認(rèn)為某事或許可能發(fā)生。might并不表示某事過去可能發(fā)生，而是表示一種虛擬語氣，指把握性不大，句中可以用may代替，不過may 要比might所表示的可能性要大。
He may/might come. You’d better stay here for a moment.
他或許來，你最好在這兒等他一會兒。
(I am not sure whether he’ll really come.)
I may/might not be back for dinner.
我可能不回來吃飯了。（I’m not sure whether I’ll be back.）
⑶用于祈使句，表“祝愿”
May you both be happy！ 祝你們倆幸福！
May you succeed！ 祝你成功！
⑷習(xí)慣搭配：may /might as well 還是…的好
You may as well give him the letter.你還是把信給他為好。
I might as well stay at home tonight. 我今晚還是呆在家里吧。
⑸在表示目的或讓步的狀語從句中構(gòu)成謂語
Write to her at once so that she may know in time.
馬上給她寫信使她及時知道。
⒊ must
⑴表示“必須”、“一定”（現(xiàn)在和未來）
We must finish this before he comes.
我們必須在他回來之前做完這件事。
⑵must 和have to：
◆嚴(yán)格說來，這兩個詞是有區(qū)別的, must表示說話人主觀認(rèn)為的“必須”，而have/has to表示客觀的需要，也可譯為“不得不”
I really must stop smoking. 我真的該戒煙了。（我認(rèn)為應(yīng)該戒）
I have to stop smoking.
我得戒煙了。（可能醫(yī)生的要求或身體的客觀情況使我戒煙）
◆have to 有時態(tài)和人稱的變化，而must沒有
I had to write some letters last night.我昨晚不得不寫些信。
I will have to meet Mr. Edward at three o’clock this afternoon.
我必須今天下午三點(diǎn)鐘去會見愛德華先生。（將來時態(tài)）
◆must not=mustn’t 表示禁止，“不許”，“一定不能”
do not have to =don’t have to “不必”
You don’t have to go now. 你不必現(xiàn)在就走。
◆must 用于疑問句時，肯定回答用must, 否定回答用need not 或don’t have/need to
Must I hand in my paper now? 我必須現(xiàn)在交嗎？
Yes, you must. (No, you needn’t. 或No, you don’t have to.)
⑶must用在反意疑問句中
在反意疑問句中，附加部分要和陳述部分的情態(tài)動詞或主要動詞在意思上相呼應(yīng)，使用情況各有不同：當(dāng)陳述部分中的must作“必須，一定要”講時，附加部分用mustn’t 或needn’t; 當(dāng)must表推測，作“一定是，準(zhǔn)是”講時，附加部分要根據(jù)must后的原形動詞選用相對應(yīng)的形式。
He must work hard at English, mustn’t he ?
他必須努力學(xué)習(xí)英語，是吧？
You must renew the book, needn’t you? 你必須續(xù)借這本書，對不對？
He must be a teacher, isn’t he ?他準(zhǔn)是一名教師，是嗎？（不說mustn’t）
You must have studied English for many years, haven’t you?
你想必學(xué)了多年英語，是嗎？（不說mustn’t）
He must have arrived here yesterday, didn’t he?
他想必昨天就到了這里，是嗎？（不說haven’t）
⑷must表示“偏偏”
The car must break down just when we were about to start off.
我們正要出發(fā)時偏偏車又壞了。
4、need 和dare
⑴need 作情態(tài)動詞，表示“需要”，只用于否定句和疑問句中，無人稱和數(shù)的變化。
We needn’t go there tomorrow. 我們不必明天去那里。
Need I tell you all the details? 我需要把一切詳情告訴你嗎？
⑵dare作情態(tài)動詞，通常用在否定句和疑問句中，無人稱和數(shù)的變化。
I dare not stand on the chair. 我不敢站在椅子上。
How dare you say such a thing? 你怎么敢說這種話？
⑶need 和dare 也可作行為動詞，與一般動詞的變化相同。
◆作行為動詞（或?qū)嵙x動詞）時，need后面接“to + 動詞原形”。
Do I need to tell you all the details? 我需要把一切詳情告訴你嗎？
You didn’t need to come. 你當(dāng)時沒必要來。
◆dare在肯定句中（I dare say除外）和疑問句中，后面都接“to +動詞原形”，在否定句中有時帶to, 有時不帶to, 如：
She dares to go out alone at night. 她晚上敢一人出去。
He did not dare (to ) do so. 他不敢這樣做。
⑷慣用語：I dare say 表示“我想”、“大概”。
There’s something wrong with the radio, I dare say.
收音機(jī)恐怕有點(diǎn)毛病。
I dare say you are right. 我想你是對的。
⑸ needn’t + have +過去分詞
表示過去本來不必做某事而實(shí)際上做了，“本不必做…”
You needn’t have come.你本不必來。 (=You didn’t have to come.) （事實(shí)上你來了）
He needn’t have waited for me.他本不必等我。（=He didn’t have to wait for me.） (事實(shí)上他等我了)
⒌will 和would
⑴表意愿、決心
在陳述句或在條件狀語從句中，wil l 和would用于任何人稱。
I will finish my lesson even if I have to stay up all night.
即使我整夜不睡覺我也一定要把功課做完。
If you will allow me, I’ll go with you.如果你愿意的話，我將跟你去。
⑵ would 可表示過去的習(xí)慣動作
He would sit there for hours sometimes, doing nothing at all.
他有時候長時間地坐在那里，什么事都不做。
Every morning I would go for a long walk.
我每天早晨都會走很長的一段距離。
⑶ 表示詢問對方的意愿或向?qū)Ψ教岢稣埱?此時，would比will 的語氣更婉轉(zhuǎn)
Will you please pass me the magazine? 請你把雜志遞給我好嗎？
Won’t you come over? 請到這邊來好嗎？
⑷ would 與like連用，表請求、提議，比will更婉轉(zhuǎn)禮貌，這時would表示的是現(xiàn)在時間并非過去時
Would you like to leave your telephone number?
請留下你的電話號碼好嗎？
⑸ will 可以表示現(xiàn)在或當(dāng)前的習(xí)慣性、經(jīng)常性、傾向性。常譯成“慣于”、“總是”
No matter what you say, he will always argue with you.
不管你說什么，他總是和你爭論。
A wise man changes his mind, a fool never will.
聰明人能隨機(jī)應(yīng)變，傻瓜是不會的。
Water will boil at 100℃. 水在攝氏100度時總是要沸騰的。
⒍shall
⑴用于第一、第三人稱疑問句，表示說話人征詢對方意見或請求指示
Where shall I put my bag? 我把包放在哪里好呢？
Shall he come in or wait outside? 讓他進(jìn)來還是在外邊等著？
⑵用于第二、第三人稱，表示意愿、期望、允諾、命令、強(qiáng)制、警告、威脅等語氣
You shall keep your room in order. 你須保持房間整潔。（表命令）
He shall be sorry for it one day, I tell you.
有一天他會后悔的，我告訴你。（表警告）
⒎should
⑴表示責(zé)任、義務(wù)、建議、勸告，用于各人稱
You should study every day. 你們應(yīng)該每天學(xué)習(xí)。（表責(zé)任）
You should always think of others before yourself.
你應(yīng)當(dāng)首先想到別人。（表勸告）
⑵表推測、可能，暗含很大的可能
I think he should be home now. 我想他現(xiàn)在應(yīng)該在家。
You should know his address.你應(yīng)該知道他的住址。
⑶should + have + 過去分詞 表過去本應(yīng)完成而未完成的動作
shouldn’t + have + 過去分詞 表示過去發(fā)生了不應(yīng)發(fā)生的動作
He should have arrived by this time.他本應(yīng)這個時候到了。（其實(shí)未到）
⑷用在why , how開頭的疑問句中或that 引導(dǎo)的從句中表達(dá)說話人感情色彩，表達(dá)意外和不滿，“竟，竟會”
I’m sorry that you should think so badly of me.
你竟把我想得那么壞，我感到遺憾。
⑸用于if 引導(dǎo)的從句中，構(gòu)成虛擬語氣
If he should drop in, give him my message.
他如果來訪，就把我的條交給他。
⑹用于建議、命令等的從句中，構(gòu)成虛擬語氣
We demanded that our wages should be raised. 我們要求提高工資。
⑺在It is necessary/ important/strange that…中：謂語動詞常用should + do, 或只用動詞原形，構(gòu)成虛擬語氣
It is necessary that he should be sent there at once.
派他馬上去那是必要的。
⒏ ought to
⑴ ought to 和should差不多，都表“應(yīng)當(dāng)”，在很多情況下可通用，但也有細(xì)微的差別：在表示因責(zé)任、義務(wù)等該做的事情時，常用ought to ，在表示某件事宜于做時，多用should.
You are his father. You ought to take care of him.你是他父親，應(yīng)當(dāng)管他。
⑵表推測，暗含很大的可能
If we start now, we ought to be able to get there in time.
如果我們現(xiàn)在動身，我們應(yīng)當(dāng)能準(zhǔn)時到達(dá)。
⑶ ought to + have +過去分詞 表過去本應(yīng)做但實(shí)際上沒做的事
oughtn’t to + have +過去分詞 表示過去本不該做但實(shí)際上做了事
I ought to have written him a letter.我本應(yīng)給他寫封信。（實(shí)際上沒寫）
I oughtn’t to have written him a letter.我本不該給他寫信。[來源:學(xué)_科_網(wǎng)]
★表示推測的情態(tài)動詞用法歸納：
⒈ 肯定句中：
must (一定)，may (可能)，might/could (也許，或許) 其語氣的肯定程度依次遞減。其中，might 和could并非過去時態(tài)，只是語氣較為委婉或可能性較小
⑴對當(dāng)前行為、情況或狀態(tài)的推測： must /may /might /could + do/be
He must/may/might/could be in the reading room.
★他肯定/可能/也許在閱覽室里。
⑵對此時此刻正在進(jìn)行的動作的推測：
must /may/ might/ could + be doing 想必/可能正在…
He must /may/ might/ could be watching TV at this time.
他此時一定/可能/或許在看電視。
⑶對過去發(fā)生的事情的推測：
must /may /might /could + have +過去分詞 想必/可能已經(jīng)…
You look very tired. You must have stayed up last night.
看上去你很疲勞，你昨晚一定熬夜了。
You may have read about it in the papers.
你可能在報(bào)上已讀到這件事了。
⑷過去的一段時間內(nèi)一直在進(jìn)行的動作：
must/may /might/ could + have + been +doing 想必/可能一直在…
He may have been waiting for us for an hour. 他可能等我們一小時了。⒉ 否定句中：
can/could not 不可能，想必不會
may/might not 可能不
⑴對當(dāng)前行為、情況或狀態(tài)的推測：
can/could not +動詞原形 不可能，想必不會
may/might not +動詞原形 可能不
He may not be busy now. 也許他現(xiàn)在不忙。
He can’t be in the reading room. I saw him on the playground just now.
他不可能在閱覽室里，我剛看到他在操場上。
⑵對此時此刻正在進(jìn)行的動作的推測：
can/could not + be doing 不可能，想必不會在干某事
may/might not + be doing 可能沒在干某事
They can’t be telling the truth. 他們不可能在說真話。
They may not be telling the truth. 他們可能沒在說真話。
⑶對過去發(fā)生的事情的推測：
can/could not + have +過去分詞 不可能，想必不會做過某事
may/might not + have +過去分詞 可能沒干過某事
He may not have achieved all his aims. But his effort is a good one.
他可能 沒達(dá)到他的全部目的，但他還是認(rèn)真做了努力的。
⑷過去的一段時間內(nèi)一直在進(jìn)行的動作：
can’t /couldn’t/may not have been doing
He can’t have been waiting for us so long.他不可能等我們那么長時間。
⒊疑問句中：
常用can/could來表示說話人的猜疑、懷疑或不肯定的語氣
⑴對當(dāng)前行為、情況或狀態(tài)的推測：
can/could + 主語+ do/be
Where can he be now? 他現(xiàn)在會在哪里呢？
⑵對此 時此刻正在進(jìn)行的動作的推測： can/could +主語+ be doing
It’s so late. Can Tom be reading? 這么晚了，湯姆還在看書嗎？
⑶對過去發(fā)生的事情的推測： can/could +主語+have done
Can she have told a lie? 她會不會說謊了？
（2011?遼寧卷）21．If you __ go, at least wait until the storm is over．【C】
A．can B．may C．must D．will
（2011?江西卷）23．___ be the postman at the door, It’s only sis o’clock．【B】
A．mustn’t B．can’t C．won’t D．needn’t
（2011?四川卷）20．The police still have I found the lost child, but they’re doing about they ．【A】
A．can B．may C．must D．should
二、虛擬語氣
1、虛擬語氣的重點(diǎn)是：
1）．一些常見的虛擬語氣的句型或結(jié)構(gòu)。
2)．虛擬語氣的特殊形式，即用來表示要求、建議、命令、提議、意愿等的主語從句、賓語從句、表語從句和同位語從句中的虛擬形式。
3)．主從句表示不同的時間概念、事實(shí)或假設(shè)情況，從而交錯成為復(fù)合虛擬語氣。
4)．含蓄條件句中的虛擬語氣的表示愿望的虛擬形式。
2、虛擬語氣的常見類型和句型
（1）由wish引起的表示愿望的虛擬語氣
A．用wish表示對現(xiàn)在的愿望時，它所引起的賓語從句中謂語動詞形式為：過去式（be動詞用were）。
B．用wish表示對將來的愿望時，它所引起的賓語從句中謂語動詞形式為：would, could, might+ 動詞原形。
C．wish用于對過去的事實(shí)表示一種不可能實(shí)現(xiàn)的愿望時，賓語從句中的謂語動詞形式為：had+動詞過去分詞或could, would + have +動詞過去分詞。
The picture exhibition bored me to death; I wish I had not gone to it.
（2）would (had) rather, would as soon, would sooner和would prefer所引起的從句中要求用過去式表示當(dāng)時或?qū)淼那闆r，用過去完成時表示過去的情況，表示希望或婉轉(zhuǎn)的責(zé)備。
I’d rather you posted the letter right away.
我倒希望你把這封信立刻寄出去。
（3）由連接詞in case, so that ,unless, lest ,for fear that引起的狀語從句中，謂語動詞要用虛擬形式，即should(might, would)+動詞原形，
She put a blanket over the baby for fear that he should catch cold.
她在那個嬰兒身上蓋上了毯子以免他著涼。
The bad man was put in the soft-padded cell lest he injure himself.
(4) 虛擬語氣在條件句中的應(yīng)用
表示與現(xiàn)在事實(shí)相反：If + 從句主語 + 動詞的過去式…，主語+should/ would/ could/ might + 動詞原形…（be 一般用were）
表示與過去事實(shí)相反：If + 從句主語 + had + 過去分詞…，主語+should/ would/ could/ might +have +過去分詞…
表示與將來事實(shí)可能相反： If + 從句主語 + ①動詞的過去式…，②should +動詞原形…， ③were to +動詞原形…， 主語 + should/ would/ could/ might + 動詞原形…
If it had not been for his help(=but for his help),we would not have succeeded.
(5) 虛擬語氣用于as if（though）引起的方式狀語從句和表語從句中，其動詞形式與wish賓語從句的形式相同。
She often laughs spontaneously, and her good humor breaks out as brightly as if it were a part of the sunshine above.
她常常發(fā)出發(fā)自內(nèi)心的微笑，而且她那美好的情緒像天上一道明亮的陽光一樣，常常流露出來。
They talked as if they had been friends for years.
他們交談著，就好像他們是我年的老朋友一樣。
(6)其它各種句型, as though, suppose, had rather, supposing, if only等等
If I were in a movie, then it would be about time that I buried my head in my hands for a cry.
二、特殊形式的虛擬語氣
虛擬語氣的特殊形式，即用來表示要求、建議、命令、提議、意愿等的主語從句、賓語從句、表語從句和同位語從句中的虛擬形式，其虛擬語氣的構(gòu)成往往是由should(可省略)+動詞原形that從句。
A、 用于表示意愿、建議、命令、提議、請求等動詞后的that賓語從句中，這類動詞有：
ask要求 advise建議 arrange安排 beg請求 command命令 decide決定 demand要求 desire渴望
determine決定 insist堅(jiān)持 intend打算 maintain堅(jiān)持主張 move建議，動員 propose提議 object反對 order命令 prefer建議 require 需要 request要求 resolve下決心 recommend推薦 suggest建議 stipulate約定，規(guī)定 urge強(qiáng)調(diào)，促進(jìn) vote公認(rèn)，提議 decree頒布（法令） pray請求
注意：這類動詞后面除了可接that虛擬句以外，也可以接doing或者to do…來表達(dá)，一般情況下，意思沒有什么差別。
She advised that we should keep the gate locked.（ 書面體）
She advised us to keep the gate locked.（口語）
She advised keeping the gate locked.(較隨便)
B、用于It is+形容詞或過去分詞+主語從句中，這類形容詞或分詞有：
advisable合理的 decided決定的 crucial關(guān)鍵的 appropriate恰當(dāng)?shù)?determined決定的 commanded命令的 arranged安排的 essential緊要的，基本的 complied遵照 anxious焦急的 imperative迫切的 important重要的 desirable合意的 better較好的，更好 insistent堅(jiān)持的 desired想要 asked請求 keen渴望的 incredible難以置信的 adamant堅(jiān)定不移的 natural自然的 insisted堅(jiān)持 necessary必要的 suggested建議 urgent緊迫的 ordered命令 shocked震驚的 vital極其重要的 possible可能的 strange 奇怪的 preferable （好一點(diǎn)） proposed提議 requested要求的 required要求的 recommended推薦 resolved決定的 probable（可能的） pity可惜，憾事 shame遺憾
注意：這類形容詞后面除了可接that虛擬句以外，也可以for…to do… 來表達(dá)，一般情況下，意思沒有什么差別。
It is essential that he should be prepared for this.
It is essential for him to be prepared for this.
C．用于由表示建議、要求、命令、請示等含義的名詞引導(dǎo)的表語從句和同位語從句中，這類名詞常見的有：
advice忠告 decision決定 demand要求 desire要求、愿望 insistence堅(jiān)持 motion提議 necessity必要性 order命令 preference偏愛 proposal提議 pray懇求 recommendation推薦 request要求 requirement要求 resolution決心 suggestion勸告、忠告
This is their resolution that extra-curriculum activities be made part of their school life.
這是他們的決議：要使得課外活動成為他們學(xué)校生活的一部分。
The motion that the remark of the last speaker be expunged from the record.該提議要求把最后一個發(fā)言的人的從記錄上除掉。
三、混合虛擬語氣
有時主句和從句的謂語動詞指不同的時間，這時需要用混合虛擬語氣。一般來說，在這種情況下，主從句謂語動詞指代的時間不同，所以我們又可以錯綜時間條件句，在這種虛擬情況，動詞形式應(yīng)根據(jù)實(shí)際情況靈活使用，在做這些題目時候尤其要注意每道題目的提示語：時間狀語。絕大多數(shù)情況下，從句或者主句都有相關(guān)的時間狀語，這是我解題的關(guān)鍵。
If you that late movie last night, you wouldn’t be so sleepy.
A. haven’t watched B. didn’t watch
C. hadn’t watched D. wouldn’t have watched 答案選C。
Many dead would now be alive if they have not attempted to return for something.
Had Paul received six more votes in the last election, he would be our chairman now.
混合虛擬語氣還有一種情況就是事實(shí)和虛擬假設(shè)的混合句，這樣的句子不僅僅是時間的不同，而重要是事實(shí)和假設(shè)的混合。
I would have gone to visit him in the hospital had it been at all possible, but I was fully occupied the whole of last week.
該句前半部分是假設(shè)虛擬，而后半部分是事實(shí)的陳述。
Your math instructor would have been happy to give you a mak e-up examination had you gone and explained that your parents were ill at the time.
該句前半句用的是假設(shè)虛擬，后半句主句也用的是假設(shè)虛擬（如果你去并且解釋的話），但是后半句的從句用的是事實(shí)語氣，因?yàn)椤案改覆×恕笔强陀^事實(shí)，故不需要用虛擬形式had been。
四、含蓄虛擬條件句
含蓄條件句是指句中沒有明顯的虛擬條件句，而是利用其他手段來暗示存在虛擬條件。但是這類隱含式虛擬條件句往往都可以轉(zhuǎn)化為if引導(dǎo)的條件句。常來表示含蓄虛擬條件的手段有：
（1）介詞或介詞短語，如but for, but that, without, in case of, under more favorable condition等。
the leadership of the party, we could not be living a happy today.=If there hadn’t been the leadership of the party, we could not be living a happy today.
A. In spite of B. But for C. Because of D. As for 答案選B。
But that she was afraid, she would have said no.
(2)連詞，如：so that, unless, in case, supposing, lest, provided(倘若……)，for fear that(唯恐)，in order that, on condition that, if only(要是……就好了)等。
She listened carefully in order that she might discover exactly what he wanted.=if she listened carefully ,she might discover exactly what he wanted.
If only I had more money, I could buy a car.
(注：lest, for fear that 和 in case 引起的從句中謂語動詞多用should+動詞原形，但可以不用虛擬語氣，而用動詞的陳述語氣形式。)例如：
The foreign teacher spoke slowly in case we misunderstood him. 這位外籍教師說得很慢以免我們聽不懂。
Care must be taken in using this method lest overflow should occur.在使用此法時要小心謹(jǐn)慎，以免會發(fā)生溢流現(xiàn)象。
（3）通過上下文及內(nèi)在含義，句中往往有but, otherwise, unfortunately等類似轉(zhuǎn)折詞。
I thought the children when we returned home, but they were still awake.
A. were sleeping B. would be sleeping C. had been sleeping D. would sleep選擇 B。
(4)形容詞及其比較級
A more careful person would not have made so many mistakes.
A less conscientious man wouldn’t have tried so hard to get this job done.
(5)分詞短語
Having known in time, we might have prevented the accident.
Born ten days earlier, the boy could have seen his late father.
(6)動詞不定式短語。一般intended/meant/hoped/wished/planned 或 was/were+不定式完成式或had intended/meant/planned/hoped/wished/+不定式一般式表示虛擬。
I intended I should call on you, but I was busy at that time.
To hear him speak French, you would take him for an Englishman.
【高考真題剖析】
（2011?陜西卷）22．I _____ through that bitter period without your generous help．
A．couldn’t have gone B．didn’t go
C．wouldn’t go D．hadn’t gone
答案【A】本題考查虛擬語氣。因?yàn)橛衱ithout your generous help．
所以是暗含的虛擬語氣。
（2011?福建卷）34．??Pity you missed the lecture on nuclear pollution。
??I it, but I was busy preparing for a job interview．
A．a(chǎn)ttended B．had attended
C．would attend D．would have attended
答案【D】本題考查虛擬語氣。由句中I was busy preparing for a job interview.可判定是與過去的事實(shí)相反，所以選擇D項(xiàng)。
（2011?全國新課標(biāo)卷）32．They have arrived at lunchtime but their flight was delayed．
A．will B．can C．must D．should
答案【D】本題考查情態(tài)動詞should的用法。Should have done表示本應(yīng)該做而實(shí)際未做。Must have done 表示過去一定做了。
（2011?陜西卷）24．?Will you read me a story ,Mummy? --OK．You____ have one if you go to bed as soon as possible．
A．might B．must C．could D．shall
答案【D】本題考查情態(tài)動詞的基本用法。Shall用于第二、三人稱表示說話人“命令、允諾、警告等”語氣。
【真題練習(xí)】
（09安徽）1. Some people who don’t like to talk much are not necessarily shy；they just be quiet people.
A. must B. may C. should D. would
【答案】B
（09北京）2. One of the few things you ____ say about English people with certainty is that they talk a lot about the weather.
A. need B. must C. should D. can
【答案】B
（09福建）. But for t he help of my English teacher, I the first prize in the English Writing Competition.
A. would not win B. would not have won
C. would win D. would have won
【答案】B 虛擬語氣。此處虛擬語氣表示與過去事實(shí)相反，句子謂語動詞用would/should/could/might + have done結(jié)構(gòu)，故選B。
（09湖南）4.? It’s the office! So you know eating is not allowed here.
? Oh, sorry.
A. must B. will C. may D. need
【答案】A 句意為：這是辦公室！因此你必須知道吃的不允許帶到這里。must表示“絕不”的意思。
（09海南）5. What do you mean, there are only ten tickets? There be twelve
A. should B. would C. will D. shall
【答案】A。 你這是什么意思，只有十張票嗎?應(yīng)該有十二人。should表示“應(yīng)該，應(yīng)當(dāng)”。
（09上海）6. It_____ have been Tom that parked the car here, as he is the only one with a car.
A. may B. can C. must D. should
【答案】C
（09四川）7. ?I don’t care what people think.
?Well, you _______
A. could B. would C . should D. might
【答案】C
【解析】考查情態(tài)動詞的用法。答話的人提了一個建議??你應(yīng)該關(guān)注別人對你的評價的。should可以用來向別人提建議，所以答案為：C
（09天津）8. This printer is of good quality. If it _______ break down within the first year, we would repair it at our expense.
A. would B. should C. could D. might
【答案】B
（09重慶）9. ?Hi, Tom. Any idea where Jane is?
?She ____in the classroom. I saw her there just now.
A. shall be B. should have been
C. must be D. might have been
【答案】C
（09全國2）10. I can’t leave. She told me that I stay here until she comes back.
A. can B. must C. will D. may
【答案】B
（09江蘇）11. He did not regret saying what he did but felt that he it differently.
A. could express B. would express
C. could have expressed D. must have expressed
【答案】C
（10安徽）32. Jack described his father, who _______a brave boy many years ago, as a strong?willed man
A. would be B. would have been
C. must be D. must have been
答案：D.
考點(diǎn)：本題考查情態(tài)動詞推測用法。
解析：句意為“杰克把他的父親描述為一個意志堅(jiān)強(qiáng)的人，他的父親多年前肯定很勇敢。”用must have been表示對過去事情的肯定推測。
（10湖南）23. You buy a gift, but you can if you want to.
A. must B. mustn't C. have to D. don't have to
答案：D
考點(diǎn)：情態(tài)動詞
解析：don’t have to 意為“沒有必要”，符合語境，句意為：“你沒有必要買禮物，但如果你想買的話，你也可以買。”
（10江西）23 I have told you the truth. ______ I keep repeating it?
A Must B Can C May D Will
答案：A
考點(diǎn)：考察情態(tài)動詞的用法。
解析： must 必須, 一定 can 可以, 能夠 may 也許 will 意愿, 傾向性動作, 前半句說我告訴你事實(shí)了, 這里用的是現(xiàn)在完成時, 表示過去的動作對現(xiàn)在造成了影響, 既然我已經(jīng)說了, 我還必須重復(fù)一遍嗎？
（10山東）25. I_____ have watched that movie ?it’ll give me horrible dreams. [來源:學(xué)科網(wǎng)]
A. shouldn’t B. needn’t C. couldn’t D. mustn’t
答案：A
考點(diǎn)：本題考查情態(tài)動詞的用法。
解析：句意應(yīng)為“我本來不應(yīng)該看那部電影的----它會使我做噩夢的。”表示“本來不應(yīng)該做而做了某事”用shouldn’t have done, 所以A項(xiàng)正確。
10天津）9. Mark have hurried. After driving at top speed, he arrived half an hour early.
A. needn’t B. wouldn’t C. mustn’t D. couldn’t
答案：A.
考點(diǎn)：考查情態(tài)動詞。
句意：邁克本來不必要那么忙的。這么高速駕駛之后，他早半個小時到達(dá)了。
解析：根據(jù)后面的語境，提前半個小時到達(dá)，說明Mark本來不必那么匆忙，所以用needn’t have done 結(jié)構(gòu)，表示“本來不必要做某事的而實(shí)際上做了”。
（10四川）3. ? I take the book out? w_w w. k#s5_u.c o*m
?I'm afraid not.
A. Will B. May C. Must D. Need
答案：B
考點(diǎn)：考查情態(tài)動詞。[來源:學(xué)科網(wǎng)]
解析：表請求可用情態(tài)動詞can, may, could, might ,表允許用can, may.
句意為：“我可以將這本書帶出去嗎？”“恐怕不行”。故應(yīng)選表情請求的情態(tài)動詞may。正確答案為B
（10全國Ⅰ）29.Just be patient .You ______ expect the world to change so soon .
A. can’t B. needn’t C. may not D. whether
答案：A
句意：耐心一點(diǎn)兒，你不能期望世界變化如此快。
解答：通過選項(xiàng)此題考察情態(tài)動詞，can't在否定句中可以表示推測，譯為不可能，，可以表示能力，譯為不能夠，也可以表示命令，不允許，但是語氣比mustn't弱，具有勸慰的意思，根據(jù)句意此題中選擇A，can't表示勸慰。
（10江蘇）25. ?I haven’t got the reference book yet, but I’ll have a test on the subject next month.
?Don’t worry. You______ have it by Friday.
A. could B. shall C. must D. may
答案：B，
解析：shall在第二人稱中表示允諾，還可以表示強(qiáng)制，命令，威脅，警告。還有在法律條文中的要求或規(guī)定。
（?陜西）23. May I take this book out of the reading room?
No, you . You read it in here.
A. mightn’t B. won’t C. needn’t D. mustn’t
答案：D
解析：考查情態(tài)動詞。英語中用could，might表示詢問或征求意見的問句中，肯定性應(yīng)答要用can或may來代替could或might，而may或might征求意見的問句否定應(yīng)答時要用mustn’t，故本題選D。
（10全國Ⅱ）17.I’m afraid Mr. Harding _________see you now. He’s busy.
A. can’t B. mustn’t C. shouldn’t D .needn’t
答案：A
解析：情態(tài)動詞考查。結(jié)合語境，根據(jù)情態(tài)動詞用于疑問或否定推測時，要用can’t。
（10湖北）79. It’s said that they have swum to the island from the continent, but they ________（不可能做到）because the ocean in between is too wide. (do)
79. 答案：can’t/ couldn’t have done it
考點(diǎn)：情態(tài)動詞
解析：當(dāng)要對過去進(jìn)行肯定的推測時，要用“can’t/couldn’t+have+done”的結(jié)構(gòu)
（10遼寧）26.Doctors say that exercise is important for health, but it _______ be regular exercise.
A．can B．will C．must D．may
答案：C
句意：醫(yī)生說鍛煉對身體重要，但是必須是有規(guī)律的鍛煉。
解析：考查情態(tài)動詞。Can一般表示“可能，或能力”；will表示“意志”；may表示“許可，可能”；must表示“必須”。
（10北京）23. ---Good morning. I've got an appointment with Miss Smith in the Personnel Department.
--Ah, good morning. You be Mrs. Peters.
A. might B. must C. would D. can
答案：B
考點(diǎn):本題考查情態(tài)動詞在語境中的運(yùn)用。
解析：第一個說話人說和史密斯小姐有約，那下面的人就回應(yīng)說，"那您一定就是Mrs. Peters了"因此排除A,C.D
（10浙江）17. “You ____ have a wrong number,” she said. “There’s no one of that name here.”
A. need B. can
C. must D. would
答案：C
考點(diǎn)：情態(tài)動詞
解析：肯定的猜測，用must
（10上海）29. ---Sorry, Professor Smith. I didn't finish the assignment yesterday.
---Oh, you have done it as yesterday was the deadline.
A. must B. mustn't C. should D. shouldn't
答案：C
考點(diǎn)：本題考查的是虛擬語氣
解析：此處表示和過去事實(shí)相反的情況，應(yīng)該用should + have + 過去分詞。本來應(yīng)該做，而未做
（10安徽）26. Bob would have helped us yesterday, but he-_______
A. was busy B. is busy
C. had been busy. D. will be busy [來源:Z&xx&k.Com]
答案：A.
考點(diǎn)：本題考查虛擬語氣與時態(tài)。
解析：前句表示對過去的虛擬，而but之后表示過去的客觀事實(shí)，故用一般過去時態(tài)。
（10湖南） 29. If he my advice, he wouldn't have lost his job.
A. followed B. should follow
C. had followed D. would follow
答案：C
考點(diǎn)：考查虛擬語氣。
解析：根據(jù)“wouldn’t have lost”可判斷if引導(dǎo)的狀語從句表示與過去事實(shí)相反的虛擬，故選C項(xiàng)。[來源:學(xué)科網(wǎng)ZXXK]
（10天津）15. John went to the hospital alone. If he me about it, I would have gone with him.
A. should tell B. tells C. told D. had told
答案：D.
考點(diǎn)：考查虛擬語氣。
句意：約翰獨(dú)自去了醫(yī)院。如果他告訴我的話，我會跟他一起去的。
解析：前一句是陳述語氣，說明動發(fā)生在過去，而且后一句的主句已經(jīng)是would have gone說明是與過去事實(shí)相反的虛擬語氣。與之對應(yīng)的從句結(jié)構(gòu)，應(yīng)該用had +過去分詞。
（10江蘇）34. George is going to talk about the geography of his country, but I’d rather he_______ more on its culture.
A. focus B. focused
C. would focus D. had focused
答案：選B
解析：would rather后應(yīng)用虛擬語氣，表示與現(xiàn)在時間相反，用動詞的過去式
（?陜西）15. If we ___ the other road, we might have arrived here in time for the meeting.
A. take B. had taken C. took D. have taken
答案：B.
解析：考查虛擬語氣。所填詞做虛擬語氣中條件狀語從句的謂語，根據(jù)主句的謂語動詞形式might have arrived可知題干是與過去事實(shí)相反，故所填部分用had+過去分詞形式，選B。
（10湖北）76. Mr. Johnson insisted that the problem worthy of attention ________ (討論) at the meeting. (discuss)
答案：(should) be discussed
考點(diǎn)：虛擬語氣
解析：“insist”引導(dǎo)的賓語從句要用虛擬，從句結(jié)構(gòu)是 “should”（可省略）加動詞原形，主語 “problem” 是要“被討論”。
（10北京）34. --The weather has been very hot and dry.
--Yes. If it had rained even a drop, things would be much better now! And my vegetables .
A. wouldn't die B. didn't die
C. had n't died D. wouldn't have died
答案：D
考點(diǎn)：本題考查虛擬語氣中對過去的虛擬。
解析：第二個說話人的If條件句是我們選擇正確答案的關(guān)鍵。要是當(dāng)時下雨了，現(xiàn)在的情況就好的多了！我的蔬菜也就不會死了。過去沒有下雨，所以我的蔬菜干死了也是發(fā)生在過去。而將句子還原則為If it had rained even a drop, my vegetables wouldn't have died.
If+ had done,主句為couldn’t/ shouldn't/ wouldn't have done.
（10浙江）10．Had I known about this computer program, a huge amount of time and energy .
A．would have been savedB．had been saved
C．will be savedD．was saved
答案： A
考點(diǎn)：本題考查虛擬語氣。
解析：根據(jù)句子的倒裝特征判斷此處是省略了if的虛擬語氣，原形是：If I had known about this computer program, a huge amount of time and energy .故選擇A。句意為：如果我早知道這個電腦程序，就可以節(jié)省大量的時間和精力了。
（2011?遼寧卷）21．If you __ go, at least wait until the storm is over．【C】
A．can B．may C．must D．will
（2011?北京卷）28．?Where are the children? The dinner’s going to be completely ruined．
?I wish they always late．【A】
A．weren’t B．hadn’t been
C．wouldn’t be D．wouldn’t have been
（2011?北京卷）24．?I don’t really like James．Why did you invite him?
?Don’t worry．He come．He said he wasn’t certain what his plans were．【D】
A．must not B．need not C．would not D．might not
（2011?江西卷）23．_______ be the postman at the door, It’s only sis o’clock．【B】
A．mustn’t B．can’t C．won’t D．needn’t
（2011?四川卷）20．The police still have I found the lost child, but they’re doing about they ．【A】
A．can B．may C．must D．should
（2011?全國II）8．If you____ smoke, please go outside．【C】
A．can B．should C．must D．may（2011?陜西卷）24．?Will you read me a story ,Mummy? 【D】
--OK．You____ have one if you go to bed as soon as possible．
A．might B．must C．could D．shall
（2011?陜西卷）22．I____ through that bitter period without your generous help． 【A】
A．couldn’t have gone B．didn’t go
C．wouldn’t go D．hadn’t gone
（2011?湖南卷）28 ．-----No one ______ be compared with Yao Ming in playing basketball．
------Oh, you are really his big fan． 【A】
A．can B．need C．must D．might
（2011?福建卷）25．------Shall I inform him of the change of the schedule right now?
-----I am afraid you _____,in case he comes late for the meeting ．【B】
A．will B．must C．may D．can
（2011?江蘇卷）34．---I left my handbag on the train, but luckily someone gave it to a railway official．
---How unbelievable to get it back! I mean, someone ______ it．【B】
A．will have stolen B．might have stolen
C．should have stolen D．must have stolen
（2011?全國新課標(biāo)卷）32．They have arrived at lunchtime but their flight was delayed．【D】
A．will B．can C．must D．should
（2011?浙江卷）11．－h(huán)ow is your new babysitter?
－We____ ask for a better one ,All our kids love her so much．【D】
A．should B．might C．mustn't D．couldn't
（2011?重慶卷）25．??Why didn’t you come to Simon’s party last night?
?? I want to ,but my mom simply _________ not let me out so late at night．【C】
A．could B．might C．would D．should
（2011?福建卷）34．??Pity you missed the lecture on nuclear pollution。
??I it, but I was busy preparing for a job interview．【D】
A．a(chǎn)ttended B．had attended
C．would attend D．would have attended
鞏固練習(xí)
1.?Are you in a hurry？
?No， in fact I’ve got plenty of time. I ___ wait.
A.must B.need C.may D.should
2.?Someone is knocking at the door. ___ it be Venis？
?No， it ___ be her； she left for New York this morning.
A.Can； mustn’t B.Might； can’t
C.May； doesn’t D.Can； can’t
3.He didn’t agree with me at first， but I ___ persuade him to sign the agreement later.
A.could B.might C.should D.was able to
4.?Is there a movie on in the cinema tonight？
?There___ be. I will phone the cinema and find it out.
A.might B.should C.can D.could
5.You ___ be careful when you cross here ? the traffic lights aren’t working.
A.can B.ought to C.might D.may
6.You ___ out last night. I called you several times， but nobody answered.
A.must have been B.must be
C.might have been D.could be
7.You ___ fail to pass the entrance examination if you don’t study harder.
A.shall B.could C.must D.should
8.When I was studying at Beijing University， I ___ take a walk along the lake every evening.
A.will B.would C.could D.shall
9.The party turned out to be a failure. I would rather ___ it.
A.not have attended B.not attend
C.not to attend D.not to have attended
10.Sir， you ___ be sitting in this seat. It is for women or children only.
A.can’t B.oughtn’t to
C.won’t D.needn’t
11.?Shall I tell Li Ming about the matter？
?No， you ___ . He has known about it already.
A.oughtn’t to B.needn’t
C.shouldn’t D.mustn’t
12.?Must I take a bus？
?No， you ___ . You can walk there.
A.must not B.don’t
C.don’t have to D.had better not to
13.?Why do you make me do so？
?I am sorry that you ___ do such a thing.
A.would B.can C.should D.may
14.?Will you stay for lunch？
?Sorry， I ___ . My brother is coming to see me.
A.mustn’t B.can’t C.needn’t D.won’t
15.What would have happened ___ ， as far as the riverbank？
A.if Bob has walked farther
B.if Bob should walk farther
C.had Bob walked farther
D.should Bob walk farther
16.Oh， Jane， you’ve broken another glass. You ought ___ when you washed it.
A.be careful B.to care
C.have cared D.to have been careful
17.It’s high time we ___ to the theater.
A.will go B.shall go C.are going to D.went
18.?Could I use your telephone？
?Yes， of course you ___ .
A.could B.will C.can D.might
19.It’s strange that they ___ nothing about this matter.
A.should know B.would know
C.had known D.knew
20.?Do you still remember the day when we went to the Great Wall？
?I can’t remember it well， but ___ sometime last autumn？
A.might it be B.could it have been
C.could it be D.must it have been
21.?I can’t get through to the general manager’s office anyhow.
?The line is busy. Someone ___ the telephone.
A.must use B.uses
C.must have been using D.must be using
22.He suggests we ___ to the cinema at once， otherwise we will be late.
A.must go B.go C.will go D.would go
23.If only he ___ me yesterday!
A.had seen B.would see C.should see D.saw
24.If you ___ wait a moment， I’ll go and find our manager.
A.can B.should C.will D.must
25.?It is rather cold here. Shall we light a fire？
?No， we ___ because things are easy to catch fire.
A.won’t B.can’t
C.mustn’t D.needn’t
26.If I ___ you， I ___ more attention to English idioms and phrases.
A.was； shall pay B.am； will pay
C.would be； would pay D.were； would pay
27.?Would you have told him the answer had it been possible？
?I would have， but I ___ so busy then.
A.had been B.were C.was D.would be
28.?Can children swim in this pool？
?Yes. However， at no time ___ they do so by themselves.
A.dare B.should
C.need D.could
29.Kunming is called“Spring City”，but it ___ snow in winter.
A.shall B.can C.must D.might
30.?What’s the matter with you？
?Oh， I’m not feeling well in the stomach. I ___ so much fried fish just now.
A.shouldn’t eat B.mustn’t have eaten
C.shouldn’t have eaten D.mustn’t eat
31.?You look so upset. What’s wrong with you？
?The door ___ . Can you help me？
A.won’t open B.won’t be opened
C.can’t open D.can’t be opened
32.?Mum，I climbed to get the Teddy Bear from the top of the shelf.
?My goodness！You ___ yourself. You mustn’t do that next time.
A.must have hurt B.should have hurt
C.may have hurt D.can have hurt
33.Children under 12 years of age in that country ___ be under adult supervision when he is in a public library.
A.must B.may C.can D.need
34.“The interest ___ be divided into five parts， according to the agreement made by both sides，” declared the judge.
A.may B.should C.must D.shall
35.?I don’t mind telling you what I know.
?You ___ . I’m not asking you for it.
A.mustn’t B.may not C.can’t D.needn’t
36.?Mum，I’ve been studying English since 8 o’clock. ___ I go out and play with Tom for a while？
?No， I’m afraid not. Besides， it’s raining outside now.
A.Can’t B.Wouldn’t
C.Dare not D.Won’t
37.?Who is the girl standing over there？
?Well， if you ___ know， her name is Mabel.
A.may B.can C.must D shall
38.The driver has drunk too much wine and dangerous things ___ happen at any time.
A. should B. can C. must D. need
39.We ___ booked. Look， this restaurant is almost empty.
A. must have B. can’t have
C. should have D. needn’t have
40.Listen! The fire engine is roaring. There ___ be a fire somewhere.
A. should B. must C. will D. ought to
【答案及部分解析】 1～5 CDDAB 6～10 AABAB
11～15 BCCBC 16～20 DDCAB
21～25 DBACC 26～30 DCBBC
31～35 ACADD 36～40 ACADB
1. may表示“可以”。
2. can用在疑問句和否定句中，表示可能性的推測。can’t表示“不可能”。
3. 情態(tài)動詞can和be able to都可表示能力。當(dāng)表示“過去成功地做了某事”時，常用was（were） able to。
4. 由下文的I will phone the cinema and find it out可知此處應(yīng)用might。may或might用在肯定句中，表示可能性的推測。
5. ought to表示勸告。
6. 題意為“我昨天晚上打了幾次電話都沒有人接，你一定是出去了”。must have done常用來表示對過去發(fā)生情況的肯定推測。
7. shall用于第二人稱或第三人稱，表示說話者的意愿，有命令、警告、威脅、強(qiáng)制、允諾和決心之意。此題用shall，表示“警告”。
8. 情態(tài)動詞would可以表示過去經(jīng)常性或習(xí)慣性的動作。與used to相比，would不含有“現(xiàn)在已無此習(xí)慣”的意義。
9. 題意為“那次聚會以失敗告終，我寧愿沒參加”。would rather （not）have done表示的是過去發(fā)生的情況。
10.由題意可知，此處應(yīng)用oughtn’t to，表示“不應(yīng)該”。
11.由he has known about it already可知，此處應(yīng)用needn’t，表示“沒有必要”。
12. don’t have to表示“不必”。
13. should常用在形容詞sorry， anxious， happy， delighted等后接的that從句中，表示“竟，會”等意義。
15.had Bob walked farther相當(dāng)于if Bob had walked farther。在虛擬條件狀語從句中，省略if時要把had， should， were等提到句首。
16. ought to have done表示“過去本來應(yīng)該做某事而事實(shí)上并沒有做到”。
17. “It’s（high或about） time”后所接從句時，從句謂語動詞常用過去式。
18. 問句中情態(tài)動詞could表示委婉客氣。
19. 題意為“他們竟然對此事一無所知，真令人奇怪”。“It’s strange， possible...+that從句”的句型中，從句謂語常用“should+動詞原形”。
20. can（could） have done表示對過去發(fā)生情況的可能性推測，常用于否定句或疑問句中。
21. must be doing表示對現(xiàn)在正發(fā)生情況的肯定推測。
22. suggest， order， demand， request等表示建議或命令等的動詞后接賓語從句，從句謂語常用“should（常省略）+動詞原形”。
23. if only表示“但愿”。如果表示現(xiàn)在的愿望，句中謂語動詞常用過去式；如果表示將來的愿望，句中謂語動詞常用“would（could）+動詞原形”；如果表示過去的愿望，句中謂語動詞常用“had+過去分詞”。
24. will表示“愿意”。
25. mustn’t表示“禁止”。
26. 表示與現(xiàn)在的事實(shí)相反，從句用一般過去時，主句謂語常用“would，could，should，might+動詞原形”。
27. had it been possible相當(dāng)于if it had been possible。but分句是描述當(dāng)時的事實(shí)，故用一般過去時態(tài)。
28. at no time（在任何時候都不）位于句首時，句子應(yīng)用部分倒裝語序。should表示“應(yīng)該”。
29. 此處用can表示“一時之可能”。
31. The door won’t open. 這門打不開。will表示“功能”，可譯為“能，行”。又如：Each classroom will seat 60 students. 每間教室能容納60名學(xué)生。
32. may（might） have done表示對過去發(fā)生情況的可能性推測，常用于肯定句中。
33. 題意為：“在那個國家12歲以下的兒童在公共圖書館時必須（must）有成年人監(jiān)護(hù)。”
34. 由judge（法官）一詞可斷定，此處有強(qiáng)制、命令的語氣，故填shall。
36. 此處句意為：“難道我不能（can’t）出去和湯姆玩一會兒嗎？”
38. should表示“很可能”。
39. needn’t have done表示“本來不需要做某事而事實(shí)上已經(jīng)做了”。
本文來自：逍遙右腦記憶 http://www.lg566.com/gaosan/79519.html
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