常用來表示含蓄虛擬條件句
① 高中虛擬語氣的用法（詳細）
一、 條件句中的虛擬語氣
1. 條件句中虛擬語氣的形式
從句中提出一種與客觀現實不相符或根本不可能存在的條件，主句會產生的一種不可能獲得的結果。條件句中的虛擬語氣根據不同的時間有三種不同的形式。
時間
從句謂語形式
主句謂語形式
將來
動詞過去式(be用were)
should + 動詞原形
were to + 動詞原形
would / should / might / could + 動詞原形
現在
動詞過去式(be 用 were)
would / should / might / could + 動詞原形
過去
had +動詞過去分詞
would / should / might / could have + 動詞過去分詞
2. 條件句中的虛擬語氣的舉例
(1) 將來時的條件句中的虛擬語氣。如：
If he should go to Qing Hua University, he would make full use of his time. 如果他要上清華大學的話，他就會充分利用他的時間了。
If he were to come here, he would tell us about it. 如果他要來的話，他會通知我們一聲。
(2) 現在時的條件句中的虛擬語氣。如：
If he were free, he would help us. 要是他有空的話，它會幫助我們的。
If he studied at this school, he would know you well. 如果他在這所學校學習的話，它會對你很熟悉。
(3) 過去時的條件句中的虛擬語氣。如：
If I had seen the film, I would have told you about it. 我如果看過這場電影，我會把電影內容告訴你了。
If I had got there earlier, I would have met Mr. Li. 如果我早點到那兒，我就會會到了李先生。
3. 運用條件句中的虛擬語氣時，須注意的幾個問題
(1) 當從句的主語為第三人稱單數時，謂語動詞若是系動詞be時，可用 was 代替 were。但在倒裝虛擬結構及 if I were you, as it were 中，只能用 were。如：
Were I ten years younger, I would study abroad. 要是我還年輕十歲的話，我會去國外學習。
If I were you, I would try my best to grasp the chance. 要是我是你的話，我要盡力抓住這次機會。
(2) 有時，虛擬條件句中，主、從句的動作若不是同時發生時，須區別對待。
①從句的動作與過去事實相反，而主句的動作與現在或現在正在發生的事實不符。如：
If I had worked hard at school, I would be an engineer, too. 如果我在學校學習刻苦的話，我現在也會使工程師了
If they had informed us, we would not come here now. 如果他們通知過我們的話，我們現在就不會來這里了。
②從句的動作與現在事實相反，而主句的動作與過去事實不符。如：
If he were free today, we would have sent him to Beijing. 如果他今天有空的話，我們會已經派他去北京了。
If he knew her, he would have greeted her. 要是他認識她的話，他肯定會去問候她了。
③從句的動作與過去發生的情況相反，而主句的動作與現在正在發生的情況相反。如：
If it had not been raining too much, the crops would be growing much better. 如果天不下太多的雨的話，莊家會長得更好。
If he had been working hard, he would be working in the office now. 要是他工作一直努力的話，他現在已進了辦公室了。
(3) 當虛擬條件句的謂語動詞含有 were, should, had 時，if 可省略，而將 were, should, had等詞置於句首。如：
Should he agree to go there, we would send him there. 要是他答應去的話，我們就派他去。
Were she here, she would agree with us. 如果她在這兒的話，她會同意我們的。
Had he learnt about computers, we would have hired him to work here. 如果她懂一些電腦知識的話，我們會已經聘用他來這里工作了(from www.yygrammar.com)。
(4) 有時，句子沒有直接給出假設情況的條件，而須通過上下文或其他方式來判斷。如：
I would have come to see you, but I was too busy. 我本該來看你了，然而我太忙了。
But for his help, we would be working now. 要不是他的幫助，我們還會在工作呢。
Without your instruction, I would not have made such great progress. 要是沒有你的指導，我不會取得如此大的進步。
(5) 有時，虛擬條件句中，主、從句可以省略其中的一個，來表示說話人的一種強烈的感情。
①省略從句
He would have finished it. 他本該完成了。
You could have passed this exam. 你應該會通過這次考試了。
②省略主句
If I were at home now. 要是我現在在家裡該多好啊。
If only I had got it. 要是我得到它了該多好啊。
二、其他狀語從句的虛擬語氣
1. 目的狀語從句中的虛擬語氣
(1) 在 for fear that, in case, lest 引導的目的狀語從句中，若用虛擬語氣時，從句謂語為： should + 動詞原形。並且 should 不能省略
She examined the door again for fear that a thief should come in. 她又把門檢查了一遍，以防盜賊的進入。
He started out earlier lest he should be late. 他很早就出發了以防遲到。
(2) 在 so that, in order that 所引導的目的狀語從句中，從句中的謂語為：can / may / could / might / will / would / should + 動詞原形。如(from www.yygrammar.com)：
He goes closer to the speaker so that he can hear him clearer. 他走近說話的人以便能挺得更清楚。
He read the letter carefully in order that he should not miss a word. 他把信讀得很仔細以便不漏掉一個單詞。
2. 讓步狀語從句中的虛擬語氣
(1) 在 even if, even though 所引導的讓步狀語從句中，可用虛擬語氣，主句、從句的結構與 if 所引導的條件從句結構相同。如：
Even if he were here himself, he should not know what to do. 即使他親自來也不知該怎麼辦。
Nobody could save him even though Hua Tuo should come here. 即使華佗在世也救不了他。
(2) 在whatever, whichever, whenever, whoever, wherever, however, no matter wh-word 等引導的讓步狀語從句中，從句虛擬語氣結構為：
① may +動詞原形(指現在或將來)。如：
We will finish it on time no matter what / whatever may happen. 不管發生什麼事，我們都要按時完成。
We will find him wherever / no matter where he may be. 無論他在哪裡，我們都要找到他。
I will wait for him no matter how late he may come. 不管他來的多麼晚，我都會等他。
② may +完成式(指過去) ，主句結構不限。如：
You mustn』t be proud whatever / no matter what great progress you may have made. 不管你取得了多麼大的進步，你也不能驕傲(from www.yygrammar.com)。
We must respect him no matter what / whatever mistakes he may have made. 不管他翻過什麼錯誤，我們必須尊敬他。
(3) 在though, although等引導的讓步狀語從句中，從句虛擬語氣結構為 should +動詞原形，主句結構不限。如：
Although / Though he should often be late, he is a good student. 盡管他經常遲到，他還是個好學生。
Although / Though he should be secretary, he must obey the rules. 盡管他是書記，他也必須遵守規定。
3. 方式狀語從句中的虛擬語氣
as if, as though 引導的方式狀語從句常用虛擬語氣。虛擬語氣的結構為：
表示所發生的時間
虛擬語氣結構
發生在主句動作之前
had + 過去分詞
與主句動作同時發生
過去時(be 用were )
發生在主句動作之後
would / could / might / should+原形動詞
例如：
They began to talk warmly as if they had known each other for long. 他們開始熱烈的談論起來就好像他們已相互認識很久了。
He coughed twice as if someone should come. 他咳嗽兩聲就好像有人要來了。
4. 原因狀語從句中的虛擬語氣
amazed, angry, annoyed, astonished, disappointed, frightened, happy, pleased, proud, sorry, surprised, upset 等後面的狀語從句中常用虛擬語氣。其虛擬語氣的結構為：
① should + 原形動詞(指現在或將來)。如：
He was angry that you should call him by name. 他很生氣，你竟然對他直呼其名。
I was astonished that he should not answer such an easy question. 我很驚訝他竟答不出如此簡單的問題。
② should + 完成式, 指過去。如：
I』m very sorry that you should have failed the exam. 我很遺憾，你這次考試竟然失敗了。
I was very surprised that Father should have known what I did yesterday. 我很吃驚，父親竟指導我昨天所作的事情(from www.yygrammar.com)。
三、賓語從句中的虛擬語氣
1．英語中，如：advise, ask, demand, desire, decide, insist(堅決要求) , order, propose, request, suggest(建議) 表示請求、要求、命令或建議等意義的動詞所接的賓語從句一般用虛擬語氣，其虛擬語氣的結構為：(should) + 原形動詞。如：
The teacher advised that we should make good use of every minute here. 老師勸我們要好好地利用在這兒的每一分鍾。
The Party asked that we should serve the people with our heart and soul. 黨要求我們要全心全意地為人民服務。
但是，當insist的意思為：堅決認為，堅持說；suggest的意思為：表明，暗含，暗示等時，賓語從句一般不用虛擬語氣。如：
Tom insisted that he hadn』t stolen the watch. 湯姆堅持說他沒有偷那塊手錶。
His smile suggested that he had succeeded in this exam. 他的微笑表明他在考試中成功了。
2. believe, expect, suspect, think, imagine 等動詞的否定句或疑問句中的賓語從句常用虛擬語氣。其虛擬語氣的結構為：should + 原形動詞。如：
Can you believe that he should kill a tiger? 你能相信他竟殺死了一隻老虎？
Can you imagine that he should take the first place in the long jump contest? 你能想像得到他在跳遠比賽中竟獲得了第一名？
3. 英語中，wish 之後的賓語從句，表示一種沒有實現或根本不可能實現的願望，常用虛擬語氣。其虛擬語氣的結構為(from www.yygrammar.com)：
表示所發生的時間
虛擬語氣結構
發生在主句動作之前
(1)had + 過去分詞；
(2)would / could / might / should + have + 過去分詞
與主句動作同時發生
過去時(be 用were )
發生在主句動作之後
would / could / might / should + 原形動詞
例如：
I wish I learnt English well. 我希望我已學好了英語。
I wish I had been there with them last week. 我希望上周跟他們一起在那兒。
He wishes we could go and play games with him. 他希望我們能去跟他做游戲。
4. 英語中，would rather, had rather, would sooner等之後的賓語從句常表示與客觀事實不相符的一種願望，故使用虛擬語氣。其虛擬語氣的結構為：
表示所發生的時間
虛擬語氣結構
過去
had + 過去分詞；
現在
過去時(be 用were )
將來
過去時(be 用were )
例如：
I』d rather you had seen the film yesterday. 我倒想你昨天看過了這場電影。
I』d rather you were here now. 我倒想你現在在這兒。
We』d rather you went here tomorrow. 我么倒想你明天去那兒。
四、主語從句中的虛擬語氣
在表達驚異、惋惜、遺憾、理應如此等意義的主語從句中常使用虛擬語氣，其虛擬語其的結構為： should + 動詞原形，主句中的謂語動詞形式不限。
句型：
(1) It is admirable / dreadful / extraordinary / odd / remarkable / sad / advisable / annoying / disappointing / surprising / upsetting / frightening / better / best / curious / desirable / important / strange / peculiar / proper / necessary / natural …that…
(2) It is a pity / a shame / no wonder…. that…
(3) It is suggested / requested / desired / proposed /…. that …
(4) It worries me that…
如：
It is important that we should do well in our lessons first. 我們先把功課學好很重要。
It is strange that he should not come. 很奇怪，他竟沒有來。
It is a pity that we should not meet last night. 真遺憾我們昨天晚上沒有見過面。
It worries me that we should be blamed for that. 我們竟要受責備真讓人煩惱。
五、表語從句及同位語從句中虛擬語氣
英語中，表示請求、要求、命令、建議等名詞advice, desire, decision, idea, instruction, order, plan, proposal, recommendation, request, requirement, suggestion, wish充當句子的主語而後面接表語從句或它們後面接同位語時，表語從表面上看幾屗及同位語從句都須用虛擬語氣。其虛擬語氣的結構為：(should) + 動詞原形。如：
We followed his advice that we should ask our teacher for help. 我們接受了他的建議：我們應該請求老師的幫助(from www.yygrammar.com)。
He told us his idea that he should go to university. 他告訴了我們他的想法：他想上大學。
His suggestion is that we should do our work more carefully. 他的建議就是我們的工作要更細心些。
Their plan is that they should build a new factory in their hometown. 他們的計劃就是在家鄉建一座新工廠。
六、定語從句中的虛擬語氣
英語中，表示：「早該做某事了」時，定語從句中的謂語動詞須用虛擬語氣，其虛擬語氣的結構為：It is (high / about) time that + 主語+ 動詞的過去式/ should + 動詞原形。如：
It is time that I went to pick up my daughter at school. 我該去學校接我的女兒了。
It is high time you should go to work. 你早該上班了。
七、簡單句中的虛擬語氣
1. 說話時，為了表示客氣、謙虛、委婉而有禮貌，言語常使用虛擬語氣。其虛擬語氣的結構形式常為：would / could / might / should + 原形動詞。如：
Would you mind my shutting the door? 我把門關起來你介意嗎？
You should always learn this lesson by heart. 你要把這個教訓牢記於心。
I should agree with you. 我應該同意你的觀點。
2. 表示「祝願」時，常用「may + 主語 + 動詞原形 + 其他」。如：
May you have a good journey! 祝你一路順風。
May your youth last for ever! 祝你青春永駐。
3. 表示強烈的「願望」、「祝願」時，常用動詞原形。如：
Long live the Communist Party of China. 中|國|共|產|黨|萬|歲。
God bless us. 上帝保佑。
4. 習慣表達中常用的虛擬語氣。
(1) 提出請求或邀請。如：
Would you like to have a talk with us this evening? 今天晚上來跟我們聊天好嗎？
Could I use your bike now? 我可以用一下你的單車嗎？
(2) 陳述自己的觀點或看法。如：
I should glad to meet you. 見到你我會很高興。
I would try my best to help you. 我會盡力幫助你。
(3) 提出勸告或建議。如：
You』d better ask your father first. 你最好先問一問你的父親。
You should make a full investigation of it first. 你應該先全面調查一番。
(4) 提出問題。如：
Do you think he could get here on time? 你認為他能按時來嗎？
Do you expect he would tell us the truth? 你期望他會告訴我們真相嗎？
(5) 表示對過去情況的責備時，常用虛擬語氣。其虛擬語氣的結構為：「情態動詞 + have + 過去分詞」。如：
You should have got here earlier. 你應該早就到這里了。
You should have returned it to him. 你應該把他還給他了。
② IF虛擬語氣的三種時態是什麼
1、提出將來會發生的事：主句：主語＋would/should/might/could＋動詞原形；
從句：should＋動詞原形/were to＋動詞原形；
2、提出現在的條件： 主句：主語＋would/should/might/could＋動詞原形；
從句：動詞過去式；
例句：If he studied at this school, he would know the enviornment around the school very much.
3、提出過去的未發生的條件：主句：主語＋would/should/might/could have＋動詞過去分詞
從句：had＋動詞過去分詞
例句： If I had read the book, I would have told you about it.
(2)常用來表示含蓄虛擬條件句擴展閱讀
if的用法
if作為從屬連詞,可引導條件狀語從句、讓步狀語從句和名詞從句。
if引導條件狀語從句,從句可為真實條件從句,也可為虛擬條件從句。如為真實條件從句,謂語用陳述語氣,表示可能性很大,作「假使」「如果」解,通常用一般現在時代替一般將來時; 如果if從句中用will,表示意願。
從句如為虛擬條件從句,謂語動詞要用虛擬語氣,表示可能性不大或與過去事實相反,作「要是,假如」解。可指過去的情況,也可指現在和將來的情況。指將來情況時可用were to或should。在現代口語中,一、三人稱後常用was代替were。if引導的虛擬條件句中,助動詞were,should,had可以移至主語前,此時if可省略。
if引導的條件從句中可以省略be和主語。
if引導的條件從句,有時後接only以加強其語氣,表示說話人非常盼望某人提出的條件能夠實現。
if可引導讓步狀語從句,作「雖然,即使」解,常和even連用。
if可引導名詞性從句,作「是否」解,常放在ask, doubt, know, learn, see, wonder等動詞後。一般用在口語中,而且不能用於句首。