第一、概念介紹，為什麼要有虛擬語氣？
語氣這個概念對我們中國學生來說比較難以理解，原因是我們漢語用極其靈活，同樣一句話，不同人說，其內涵都有差異。不如說：“你真行！” 這三個字就可以表達好多不同的涵義。一種是誠心誠意的讚美；當夥伴做了過格的事，你也可以說“你真行！”，略表責備；如果把“真”聲調提的高一點，就有一種驚訝……這些讓給語言大師們研究去吧！由於中國人表達注重意念，所以漢語的句子也就構建在意念主軸上（thought-pivot），句子強調的是意義，而不是結構。我們經常看到也說一些沒有主語，沒有謂語的句子，但我們一聽就明白對方在說什麼。就拿剛才的例子，不同的人，不同場合，都有不同的意思，但聽話人不傻的話，就可以體會到對方的心意。英語句子構建在形式（或主謂）主軸（form-pivot）上，它強調句子的結構的完整和嚴密，絕大多數的句子都需要主語和謂語。一句話就是漢語注重意念，英語注重形式。表達不同的時態，語態，語氣必須有相對應的句子形式。
漢語的名詞不會改變自身的形式變為複數，動詞不用改變自身的形式表示過去時，現在時或將來時，漢語詞語組合成句依靠詞序（word order）和增減虛詞就可以了。比如，“鳥兒們飛出籠子了。”這裡的“們”就是把名詞變成了複數，“了”就相當於過去時，這樣是不是非常簡單。英語完全不同了，它必須通過改變詞的形式，和語序來實現這些功能。比如，table/ tables(複數，幾張桌子)，the boy‘’s (所有格，所屬關係)，run/ ran (過去時)/ run(過去分詞)
對比下面的漢英句子形式，就可以說明這兩種語言的差別。
他唱歌。he sings a song.
他正在唱歌。he is singing a song.
他正在唱歌嗎？is he singing a song?
漢語每一個字的形式沒有變化，英語變化較多，語序變化較大。
第二、什麼是虛擬語氣？
語氣，就是動詞的一種形式，表示說話人對說話內容的看法和態度。如果表示說話人認為他說的是事實，就用陳述語氣;如果表示說話人提出要求,命令或勸告就是祈使語氣;如果表示說話人認為他所說的話是和事實相反的,一種主觀設想,一種主觀願望,就是虛擬語氣.
He is a clever boy.陳述語氣
China is so famous for its long history.陳述語氣
Be quick or you’ll be late.祈使語氣
Go down this street.祈使語氣
重點說說虛擬語氣，一個人看到別人買了電腦，心裡可能不舒服。他可能說：
如果我有足夠錢，我也給自己買一臺電腦。（他這麼說的時候，他沒有錢，是不是與現實相反的，他只是在表達一種設想願望）漢語表達完全看不出來什麼語氣變化，完全靠說話事的語境，英語，死腦經啊 他必須通過詞形變化，語序變化來實現，而且這個變化都是固定的。
If I had enough money, I would buy a computer. (虛擬語氣，表示的對現在的假設，現在的願望，或者乾脆說與現在相反，因為現在他沒有錢，買電腦當然就是虛擬的了)
If I have enough money, I will buy a computer(這就是稱述語氣，對比看看，區別在什麼地方，通過詞形的變化，來表達這種願望和假設。)
還是這個人，他囊中羞澀，買不了電腦，所以他就說了，如果我當初好好讀書，考個好大學，有一份好的工作，我就不會囊中羞澀了，我就有錢買電腦了。這時候他就是對過去的事實的假設，這句話就可以這麼說了：
If I had had studied hard, I would have had a good job. 在對比一下這個句子，又改變了形式。
這就是對過去的假設，當然更不切合實際了，歪果仁自然在句子形式上，寫得更加有變化了。同樣也可以對將來做不切合實際的假設，比如如果明天我當上了美國總統，我就拆掉美墨邊境牆。如果三年後我成為NBA明星，我就在合肥建一所籃球學校。這三種虛擬語氣的結構都是固定的。應該說英語文章是比較好懂的，只要看到這樣的句式，就基本上可以判斷作者的意圖。
不現實的假設啊！外國人死腦經嘴上都說出來了！
下面介紹這些變化的規律：
第三、虛擬語氣如何組成？
一、含有條件狀語從句的複合句(以do為例;S=主語)
時間 條件狀語從句 主 句
現在 If +S+did (were) S+would/should/could/might +do
過去 If +S+had done S+would/should/could/might + have done
將來 If+S should do / were to do S+would/should/could/might +do
例如:
①If I were you, I would apply for the job. 與現在相反
②If I had the money, I would buy it.與現在相反
③If I were given another chance，I would do it better.與現在相反
④If I had taken your advice, I would have made great progress.與過去相反
⑤If it had not been for your help, I wouldn’t have finished the work so easily.與過去相反
⑥If it should rain tomorrow,I would stay at home all day. 與將來相反
⑦If you were to come tomorrow,I could wait for you at home.與將來相反
注意：在書面語中，條件從句可以不用連詞if，而將謂語中的were，had或 should 等移至主語之前構成倒裝句。例如：
①Were I you, I would apply for the job.
②Had I taken your advice, I would have made great progress.
③Should it rain tomorrow,I would stay at home all day.
二、錯綜時間的條件句
虛擬條件句中的主句和從句涉及的動作發生的時間不一致，這時主句和從句的謂語形式應按照各自動作發生的實際時間來表達。例如：
①If you hadn't watched TV yesterday, you wouldn't be so sleepy now. （從句yesterday說明過去，主句now說明現在）
②If they had left home early this morning, they would arrive in half an hour. （從句說明過去，主句說明將來。）
③If you hesitated this moment, you might suffer in the future. （從句說明現在，主句說明將來）
三、含蓄條件句
非真實條件句中的條件從句有時不表達出來，只暗含在上下文中，這種句子叫做含蓄條件句。含蓄條件句有三種情況：
1．條件暗含在單詞短語中：常見介詞有with假如有, without假如沒有, but for要不是因為； 連詞有or/ ：otherwise（前句用陳述語氣，後句用虛擬）；but（前句為虛擬，後句陳述）例如
①He would not get such a result without your help. (條件暗含在介詞短語without your help= if you hadn’t helped him中)
②But for you, I could not be recovered so soon. (條件暗含在But for you= If you hadn’t helped me中)
③He must have been there, or he never could know the place so well.(暗含條件是連詞or；後句為虛擬)
④I would have been to your place, but I was really too busy.
=I was really too busy, or/ otherwise I would have been to your place.
⑤She was ill, otherwise she would have been present at the meeting. （條件通過連詞otherwise/ or表示出來 If she had not been ill...）
2．條件可根據上下文推理出
①They could have won.(條件可能是if they had been patient )
②Such mistakes could have been avoided.（條件可能是if you had been more careful ）
③Why didn't you tell me about it I should have helped you.（條件可能是if you had told me about it）
④-- Did you go to see him yesterday?
-- I would have, but someone come to visit me.（條件是if no one had come to visit me）
3．條件用其他形式來表示
①Suppose you were in my shoes, what would you do? （用suppose/ supposing/ providing等詞表示if）
②To talk with her, you would know she could not hear well.（不定式有假設的意思，相當於If you should talk with her...）
③Left to himself, he could not have finished the work.（動詞的-ed形式表示條件 If he had been left to himself...）
二. 虛擬語氣用在賓語從句中
sb. did（were）…（表現在）
1. wish+that sb. had done… （表過去）
sb. would/could do…（表將來）
例如：
①I wish I knew his address.
②I wish he hadn’t been rude to his parents.
③He wishes we would go with him.
2.would rather後的從句要用虛擬語氣。
例如：
①I’d rather you posted the letter right away. (現在)
②I’d rather I hadn’t said such unkind things to you.（過去）
③I'd rather you came here for the answer tomorrow .（將來）
3. 表示“堅持、建議、決定、要求、命令”（“堅決要命”）等主觀意向的動詞之後的賓語從句，謂語用should＋do，should可省略(注意：被動語態用should+be+done)。這類詞有：insist，suggest，advise，recommend，propose，decide，determine，demand，request，require，desire，order，command等。例如：
①The expert proposed that TV should be turned off at least one hour every day.
②Experiments demand that accurate measurements be made.
③She insisted that we should take up the matter at the meeting. 虛擬語氣
注意考點：
1. suggest 有多個意思，當表示“暗示、表明”時，用陳述語氣。比如：他蒼白的面色暗示他糟糕的健康了His pale face suggests his poor health.或者Your pale face suggests that you are ill.如果表示建議別人去做什麼就要用 suggest doing sth ,從句時就是suggest that + sb (should) do sth . 這就是表示“堅持、建議、決定、要求、命令”（“堅決要命”）等主觀意向的動詞之後的賓語從句，謂語用should＋do，should可省略。也是虛擬語氣的一種同樣道理 insist 表示“堅持說、堅持認為（某個事實）”時，用陳述語氣。例如：
②He insisted that he hadn’t stolen the money.用陳述語氣 非虛擬語氣。
三. 虛擬語氣用在主語從句中
It is demanded / necessary / a pity + that…等結構的主語從句，謂語動詞用should do，should 可省略。
(注意：被動語態用should+be+done)。
例如：
①It is required that the students should not use mobile phones in their school.
②It’s necessary that college students should master at least one foreign language.
四．虛擬語氣用在同位語從句中。
表示“堅持、建議、決定、要求、命令”（“堅決要命”）等主觀意向的名詞後同位語從句需用虛擬語氣，其表達形式為should ＋do，should可以省略(注意：被動語態用should+be+done) 。這類名詞常見的有：advice，suggestion，proposal，order， demand，desire，request，requirement，recommendation等。例如：
①He gave orders that the work (should) be started at once.
②We are all for your proposal that the discussion ( should ) be put off．
五． 虛擬語氣用在表語從句中。
表示“堅持、建議、決定、要求、命令”（“堅決要命”）等主觀意向的的名詞作主語時，表語從句需用虛擬語氣，其表達形式為should ＋do，should可省略(注意：被動語態用should+be+done)這類名詞主要有：advice, suggestion, order, proposal,demand,desire, request, requirement, recommendation等。例如：
①My suggestion is that the mayor (should) present the prizes.
②His plan is that he should pass the exam first.
六． 虛擬語氣用在定語從句中
It is（about/high）time＋that sb.did sth/should do sth. （注意：本句型中should不可省略）例如：
①It's about time that we went home.
②It’s high time that we should go home.
注：在It/This/That +be+ the first time／second time that．．．句型中，從句中謂語動詞用完成時態。例如：
①This is the first time that I have visited Hongkong.
②That was the third time that he had made the same mistake.
七. 虛擬語氣用在讓步、方式、目的、不用if的條件狀語從句中
1．在帶有even if/ even though引導的讓步狀語從句的主從複合句中，主句和從句都用虛擬語氣，動詞形式與含有非真實條件句的虛擬語氣相同。例如：
①Even if he had been ill, he would have gone to his office.
②I wouldn’t buy it even though I had money.
2.由as if或as though引導的狀語從句表示比較或方式時。從句謂語形式為動詞的過去式(be用were)或 “had十過去分詞”。例如：
①He treated me as if I were a stranger.
②She talked about the film as if she had really seen it.
3．虛擬語氣用在lest（唯恐、免得），for fear that及in case引導的目的狀語從句中。 在由lest等引導的目的狀語從句中需用虛擬語氣，表示“以防，以免”等意思，其謂語動詞多由“should ＋動詞原形”構成，should也可省略。例如：
①He was punished lest he should make the same mistake again．
②He handled the instrument with care for fear (that) it should be damaged.
③Take some more money with you in case you should need it.
④He can use the car on condition that he should return it tomorrow.
八．虛擬語氣用情感語言中
If only sb./sth. +時態後退型的謂語。例如：
①If only you were here now.
②If only I had known the result of the examination.
九．情態動詞+have done的其他用法
1.must have done ：肯定/一定做過（某事）。例如：
①It must have rained last night, for the ground is wet.
②You must have been mad to speak to such a fool.
③His i-phone must have been stolen by someone,he could’t find it anywhere.
2.can’t/couldn’t have done:不可能做過（某事）；一定沒做過（某事）。例如：
①I didn’t see her in the meeting room this morning. She couldn’t have attended the meeting.
②He can’t have gone abroad，I saw him a moment ago.
3.may/might /could have done:可能做過（某事）。例如：
①He may/could have broken up with his girlfriend.
②He might have given you help, even though he was busy.
4.may/might not have done：可能沒做過（某事）。例如：
①He may not have seen that film.
②They may not have known it beforehand.
5.should have done/ought to have done：本來應該做某事（而沒做）。例如：
①You should have finished your work on time.
②I ought to have gone home last Sunday.
6.should’t have done/ought’t to have done：本不應該做某事（而做了）。例如：
①You shouldn’t have put your book on the bed.
②He ought’t to have blamed you,it’s not your fault.
7.could have done：本來可以做某事（而沒做）。例如：
①You could have passed the exam,you were too careless.
②He could have worked in Wuhan after graduation,but he decided to work in the remote countryside.
8.needn’t have done：本來沒必要做某事（而做了）。例如：
①You needn’t have come so early.
②You needn’t have taken my umbrella on such a fine day.
9.would have done ：本來會做某事；就已經......例如：
①He would have come to help me ,but he was too busy then.
②If I had taken your advice, I would have made great progress.
高考短文改錯及語法填空分析與訓練·虛擬語氣與情態動詞
考點規律分析：短文改錯及語法填空對虛擬語氣和情態動詞的考查主要涉及情態動詞的選擇、情態動詞的否定表達、情態動詞後面接動詞原形、should+動詞原形構成的虛擬語氣以及時態後退型的虛擬語氣。
虛擬語氣短文改錯及語法填空真題訓練：
1．(2016·全國Ⅰ，閱讀A)When Sandra Day O’Connor finished third in her class at Stanford Law School in 1952, she ________not find work at a law firm because she was a woman.
2．(2016·全國Ⅱ，短文改錯)We can chose between staying at home and taking a trip.
3．(2016·全國Ⅱ，短文改錯)Some classmates suggest we can go to places of interest nearby.
4．(2016·北京，31)I love the weekend, because I________get up early on Saturdays and Sundays.
5．(2016·浙江，17)George ________(go) too far .His coffee is still warm.
6．(2015·北京，29)—Can't you stay a little longer?
—It's getting late.I really ________ go now.My daughter is home alone.
7．(2015·浙江，4)It was so noisy that we ________ not hear ourselves speak.
8．(2015·重慶，12)You ________ be Carol.You haven't changed a bit after all these years.
9．(2015·陝西，21)You ________feel all the training a waste of time，but I'm a hundred percent sure later you'll be grateful you did it.
10．(2015·四川，2)You ________ be careful with the camera.It costs!
11．(2015·福建，27)—Sorry, Mum! I failed the job interview again.
—Oh, it's too bad.You ________ have made full preparations.
12．(2015·天津，7)I ________have worried before I came to the new school, for my classmates here are very friendly to me.
13．(2014·北京，27)________ I have a word with you? It won't take long.
14．(2014·湖南，25)—I've prepared all kinds of food for the picnic.
—Do you mean we________ (not)bring anything with us?
15．(2014·江蘇，31)It was sad to me that they，so poor themselves，________bring me food.
16．(2014·江西，30)Life is unpredictable；even the poorest ________become the richest.
虛擬語氣短文改錯專項訓練：
1. It is high time that you leave for Shanghai.
2. She suggests that her brother not goes to college.
3. The judge insisted that the spy was put in prison.
4. How I wish I am as strong as you.
5. It is necessary that the patient is sent to hospital right away.
6. If he hadn’t been caught in the storm yesterday, he will not be ill now.
7. If I am you, I would give him a good beating.
虛擬語氣短文改錯及語法填空真題訓練：
I.1．could [根據句意：當桑德拉在法律學習畢業之後，因為她是女人，沒能在法律公司找到工作。]
2．chose→choose [考查動詞原形。根據語法知識可知，情態動詞can後要用動詞原形。]
3．去掉can或can→should [考查固定表達。suggest表示“建議”，後面的賓語從句要用should do形式，should可以省略，故答案有兩種改法。]
4．needn’t [考查情態動詞。句意：我喜歡週末，因為每逢週六、週日我不需要早起。]
5．can’t have gone [考查情態動詞。句意：喬治不可能已經走得太遠。他的咖啡溫乎。can’t have done表示對過去否定的推測，意為“不可能做了……”。]
6.must [句意：——你不能再多待一會兒嗎？——天要黑了，我真的現在必須走了，我的女兒獨自呆在家裡。must必須。]
7．could [句意：太吵鬧了，我們連自己說的話都聽不到。can/could表示“能力，能夠”。根據前面的was可知，此處要用過去時could。]
8．must [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。]
9．may [句意：你也許會認為所有的培訓都是浪費時間，但是我百分之百的保證你以後會感激你所做的事情。考查情態動詞。根據後文的描述可以看出此處培訓還沒有結束，是一種不肯定的推測語氣。]
10．must [考查情態動詞。句意：你一定要非常小心對待照相機，它很昂貴。此處表示命令語氣。]
11．should [句意：——很抱歉，媽媽，我的面試又失敗了。——噢，真是太糟糕了，你本應該做好充分準備的。考查情態動詞＋have done的意義。根據上句的面試又失敗了，可知是對過去事實的虛擬。should have done本應該做但是沒有做。]
12．needn't [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。]
13．Can 14.needn't 15.should 16.might
虛擬語氣短文改錯專項訓練：
1. leave改為left。It is time後面的從句動詞要用虛擬語氣。謂語動詞用過去式。
2. goes改為go。suggest表示“建議”，後面的賓語從句用虛擬語氣。謂語動詞用原形。
3. was改為be。賓語從句要用虛擬語氣。
4. am改為were。wish後面的賓語從句需用虛擬語氣。
5. 第二個is改為be。主語從句要用虛擬語氣。
6. will 改為would。此處要用虛擬語氣。
7. am 改為were。這是一個與現在情況相反的一個假設，要用虛擬語氣。
