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if引導的虛擬語氣應該用什么時態
1. 表示與現在事實相反的情況，其句型為“ if+ 主語 + 動詞的過去式（ be 動詞用 were ），主語 +would / could / might / should + 動詞原形”。如：
If the weather were fine, we would go to Shanghai.
如果天氣好，我們就去上海。（事實上天氣不好）
If they had time, they would / could / might go with me.
如果他們有時間，他們就會（可能）和我一起去。
2. 表示與過去事實相反的情況。其句型為“ if + 主語 + 動詞的過去完成式，主語 +would / could / should / might + have + 動詞的過去分詞”。如：
If I had taken his advice, I shouldn't / wouldn't / couldn't have made such a mistake.
如果我按照他的建議去做，我一定不會（不可能）犯這樣的錯誤。
3. 表示與將來事實可能相反的假設和結果，其句型為“ if + 主語 + 動詞的過去式 / should + 動詞原形 / were to +動詞原形，主語 +would / could / might / should + 動詞原形”。如：
The glass would break if you dropped it.
杯子摔下來會打破的。（事實上沒有摔下來）
If it should rain, the crops would / could / might be saved.
假如天下雨，莊稼就一定（有可能）會得救。
if引導的虛擬語氣
if從句的虛擬語氣原理： 1、如果句子在想象現在發生而實際未發生的事件，由現在時倒退成過去時： （從句）if+過去時，（主句）4個情態動詞+動詞原形 2、如果句子在想象將來發生而實際不會發生的事件，由將來時倒退成過去時，所以與1是一樣的，但是此處從句有三種： （從句）if+過去時/if+were to do/if+should do，（主句）4個情態動詞+動詞原形 3、如果句子在想象過去發生而實際沒有發生的事件，有過去時倒退成過去完成時： （從句）if+過去完成時，（主句）4個情態動詞+have done 擴展資料發音：英 [?f] ；美 [?f] 釋義 1、conj. （表條件）如果；即使；是否；（表假設）假如 ①（表示條件）如果 ②（表示虛擬）假如，要是 ③（表示讓步）即使 ④是否 ⑤（表示因果關系）每一次。
的時候（總是會） 2、n. 條件；設想 參考資料：百度百科-if。
【if引導的虛擬語氣】
if引導的條件句中的虛擬語氣if引導的條件狀語從句可以分為兩類：真實條件句（Sentences of Real Condition）和虛擬條件句.凡是假設的情況發生性可能很大，就是真實條件句；當假設是不大可能實現時，就是虛擬條件句.如：If I have time,I will help you with this work.如果我有時間，我會幫助你做的.If time permits,we'll go fishing together.如果有時間的話，我們就一起去釣魚.If I were you ,I would have attended the meeting.我要是你的話，就去參加會議了.If he had come here yesterday,he would have seen his old friend.假如他昨天來這兒的話，就會看見他的老朋友.下面我們一起看看if在條件狀語從句中的虛擬語氣.1.表示與現在事實相反的情況.其句子結構為：從句：if + 主語+ 動詞的過去式（be 用were） + ……主句：主語+ would (should,could ,might) + 動詞原形+ ……If I were you,I would read it again.如果我是你的話，我再讀一遍.（事實上我不是你）If he hurried,he could catch the first bus.他要是快點能夠趕上頭班公共汽車.（可他不急）If she knew English,she would not ask me for help.如果她懂英文，她就不必要我幫了.2.表示與過去事實相反的虛擬條件句.其句子結構為：從句：If + 主語+ had +過去完成式動詞+ ……主句：主語+ would (should,could,might) + have +過去完成式動詞+……If you had taken my advice,you would not have made such a mistake.如果你聽了我的勸告，就不會犯這樣的錯誤.（事實上你沒有聽我的勸告）If it had rained yesterday,we would have stayed at home.如果昨天下雨的話，我們就會留在家里.If I hadn't been ill yesterday,I might have come to school.昨天要是不生病，我是可能來上學的.（事實上我生病了）If you had studied harder last term,you could have passed the exam.如果你在上個學期用功一些，你就會在考試中過關了.3.表示與將來事實相反的虛擬條件句 （對將來的事實實現的可能性不大）.其句子結構為：從句：If + 主語+ should （或were） + 動詞原形+……主句：主語+ would (could,should,might) + 動詞原形+……If it should rain tomorrow,I would stay at home.如果明天下雨的話，我將待在家里.（根據天氣情況，明天不可能下雨）If he came tomorrow,I would do it with him.如果明天他來的話，我將和他一起做此事.（事實上他來的可能性很小）If he were here,I would give him the books.如果他在這兒，我可能會把書給他.。
關于if的虛擬語氣
有時你也可以選擇用could或 might，但是如果是選擇題的話肯定不能這些詞都在選項里，那就又好幾個答案了。
沒法選了。我做四級的時候就碰到過各種虛擬語氣的題， 比如有的要倒裝，有的前半句用虛擬、后半句用真實語氣。
。這都要讀懂題判斷的、、、 下面是總結。
。你參考參考、1. 虛擬語氣在if條件狀語從句中的用法 與現在事實相反：（從句謂語動詞）動詞的過去式（be用were而不用was） （主句謂語動詞） should/ would /could/ might+動詞原形 與過去事實相反：（從句謂語動詞） had + 過去分詞 （主句謂語動詞） should/ would/could/might + have+過去分詞 與將來事實相反：（從句謂語動詞）*+動詞原形 2.動詞過去式 * to+動詞原形 （主句謂語動詞） should/ would/ could/ might +動詞原形2. Wish 引導的賓語從句 與現在事實相反 ： 過去時（were） 與過去事實相反 ： had+過去分詞 與將來事實相反 ： would/could/might+動詞原形 eg. I wish I were a bird. I wish he hadn't done that. (do) I wish I would be rich in the future. 3. 表示要求，命令，建議的虛擬語氣 Keys:1). insist 2). order, command 3). advise, suggest, and propose 4). demand, require, request, desire 這些動詞后面的賓語從句要使用虛擬語氣用法。
即從句中的動詞使用should + 動詞原形， 或者省略should.直接家原形 eg. The doctor suggested that he (should) try to lose his weight. He insisted that we (should) tell him the news. 虛擬語氣（二） the Subjunctive mood （假設語氣）1. 表語從句、同位語從句中的虛擬語氣 在suggestion, proposal, order, plan, idea, advice, decision等需要有內涵的 名詞后面的表語從句、同 位語從句中，要使用虛擬語氣。其謂語動詞應用：should+原形動詞。
另外連接從句的that不能省略。 eg. My suggestion is that we should go there at once. What do you think of his proposal that we should put on a play at the English evening?2、 It's necessary/strange/natural/ important/pity/no wonder/impossible + that Clause 從句中的動詞要用虛擬， 即（should）+動詞原形 eg. It is strange that he (should) say so. 他居然會這樣說，真是奇怪。
It is a great pity that you (should) think so. 他居然會這樣想，真是一件憾事。 It is natural that a bird (should) rest in trees. 鳥在樹上安歇是很自然的。
3、 在It is/was suggested /ordered / demanded / proposed / etc. 結構中要使用虛擬語氣 eg. It's requested that we (should) keep the stability of the society for the people's peaceful life. It's suggested that the plan be carried out. It is ordered that all the troops (should) withdraw three miles away. 根據命令，所有 部隊撤至三英哩以外。 It is arranged that he leave for Canada on Friday. 照安排，他星期五動身去加拿大。
It is suggested that the English evening be held on Saturday. 4. would rather 后的賓語從句。 eg. I would rather you could teach me again. The manager would rather that his secretary went to the meeting instead of him .經理 寧愿他的秘書代替他去開會。
5. as if, as though引導的從句。 以as if 、as though（似乎，仿佛）引出的方式狀語從，如果表示真實情況應該用直陳語 氣；如果表示非真實情況則應該用虛擬語氣， 其謂語動詞的虛擬式與wish后面賓語從句中謂 語動詞的虛擬式相同。
eg. The little boy knows so many things as if he was a man.6. 由if only （要是……，那該多好啊！）引導的驚嘆句。如： If only I had passed the test ！比較if only與only if: only if表示"只有"；if only則表示"如果……就好了"。
If only也可用于陳述語氣。 eg. I wake up only if the alarm clock rings. 只有鬧鐘響了，我才會醒。
If only the alarm clock had rung. 當時鬧鐘響了，就好了。 If only he comes early. 但愿他早點回來。
7. It is (high) time that It is (high) time that 后面的從句謂語動詞要用過去式或用should加動詞原形，但should不可省略。 eg. It is time that the children went to bed. It is high time that the children should go to bed. It is high time that we had our lunch. 該是我們吃午飯的時候了。
It is time that he made up his mind. 該是他作出決定的時候了。
IF虛擬語氣的三種時態是什么
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. 擴展資料 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，表示意愿。
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、三人稱后常用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，有時后接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等動詞后。一般用在口語中，而且不能用于句首。
英語IF虛擬語氣的用法
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。
例句：If he should go to Harvard University, he would make full use of his time.
如果他要上哈佛大學的話，他就會充分利用他的時間了。
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.
如果他在這所學校學習的話，他會很了解周邊環境。
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.
我如果看過本書，我會把內容告訴你了。
擴展資料
if短語的用法
1、as if
1）釋義：猶如，好似
2）例句
As if it never happened.
如果它從來沒有發生過。
2、if any
1）釋義：若有的話；即便要
2）例句
What action, if any, do you take?
若有的話，你會采取什么措施？
3、if so
1）釋義：如果是這樣的話；要是這樣
2）例句
If so you have not yet forgiven.
如果是這樣，你還未能學會寬恕。
4、if only
1）釋義：只要；要是…多好
2）例句
If only I could go with you.
要是我能和你一起去就好了
5、if ever
1）釋義：假如，要是；如果真有（我當真）
2）例句
If ever we do not feel like eating, do not force us.
當我們不想吃飯的時候請不要強迫我們。
6、if at all
1）釋義：如果某事真會發生的話；如果某人真要做某事的話
2）例句
How, if at all, should the Department of Homeland Security be restructured?
如果要重組國土安全部的話，應該如何重組？
7、if and when
1）釋義：萬一，如果；只有當…之時
2）例句
Be unique if and when replicated to another.
如果是獨一無二的，當復制到另一臺。
If引導虛擬句
虛擬語氣是英語中用來表示對不可能發生的事物的一種猜測或假設的語氣。
英語中的虛擬語氣常見的類型有：條件狀語從句中的虛擬語氣，后賓語從句中的虛擬語氣，某些動詞后賓語從句中的虛擬語氣，某些結構后主語從句中的虛擬語氣等。 "if"條件狀語從句中的虛擬語氣的結構如下表：虛擬類型從句主句 對現在情況的假設一般過去時would+動詞原形 對將來情況的假設一般過去時would+動詞原形 對過去情況的假設過去完成時would + have + 過去分詞 一、對現在情況的假設 主要表示對不可能發生或不太可能發生的現在情況的假設，例如：1) If you were an Inuit near the North Pole, you would enjoy the raw meat from seals.2) If you were a man living in the grassland, you would prefer the roasted meat of sheep or goats.3) If you were in Germany, you would find soup that is thick and heavy.4) If you were in China, you would find soup that is thin and clear. 以上各句所體現都是條件狀語從句中的虛擬語氣，表示對不可能發生或不太可能發生的現在情況的假設。
對現在情況假設的虛擬語氣的構成如下： 1）條件狀語從句中用were，而主句中則用would + enjoy 構成2）條件狀語從句中用were，而主句中則用would + prefer 構成3）條件狀語從句中用were，而主句中則用would + find 構成4）條件狀語從句中用were，而主句中則用would + find 構成 二、對將來情況的假設 1) If I had enough time, I would certainly go.2) If you hurried up, you would catch that train.3) If you studied hard in college, you would find a good job in the future.1.如果我有足夠的時間，我一定會去。2.如果你快一點，你還會趕上那趟列車。
3.如果你在大學里努力學習，將來你就會找到一份好工作。 對將來情況的假設的虛擬語氣的構成如下： 1）條件狀語從句中用had，而主句中則用would + go 構成2）條件狀語從句中用hurried，而主句中則用would + catch 構成3）條件狀語從句中用studied，而主句中則用would + find 構成 三、對過去情況的假設 1) If you had begun to do your homework earlier, you would have completed them.2) If I had listened to the teacher, I would have finished reading the English book.3) If Tom had prepared the mid-term exam well, he would have passed it.1）如果你早點開始做家庭作業，你早就做完了。
2）如果我聽了老師的話，我該把這本英語書看完了。3）要是湯姆為其中考試做了充分準備，這次其中考試他就及格了。
對過去情況假設的虛擬語氣的構成如下： 1）條件狀語從句中用had begun，而主句中則用would + have + complete構成2）條件狀語從句中用had listened ，而主句中則用would + have + finished構成3）條件狀語從句中用had prepared，而主句中則用would + have + passed 構成 四、條件句虛擬語氣中的情態動詞該如何選用？ 條件句虛擬語氣中的情態動詞是否只能使用would條件句虛擬語氣主句除了可使用would外還可以便用might, could和should。其中should多用于第一人稱后。
在美國英語中在第一人稱后多用would。1) If I have enough time, I should have finished it. 如果我有足夠的時間，我會完成它的。
2) If he hadn't been ill, he might have come. 要不是生病，他可能就來了。3) If I had been more careful, I could have done better. 我要是細心一點，是可以做得更好的。
五、條件句虛擬語氣從句中的be動詞的正確形式是 條件句虛擬語氣中從句中的be動詞不管是什么人稱，多用were形式。但在非正式特別是口語中，第一、三人稱單數也可以使用was。
1)If he were here now, he would give us a hand. 如果他現在在這兒，他會幫助我的。2)If I were you, I would not go. 如果我是你，我是不會去的。
3)If she was here, we could ask her.如果她在這兒，我們可以問她。六、條件狀語從句中的虛擬語氣的倒裝形式是 當條件句虛擬語氣的從句中含有"be, have, should, could四個詞，從句可以倒裝。
倒裝的形式是把這四個單詞提前至句首，將If省略，剩下的句序不變。1) Were I you, I would study hard. 如果我是你，我就會好好學習。
2)Had I had enough home, I would have done it better.如果我有足夠的時間，我會把這件事做得更好。3) Should John come now, what would you say to him？ 如果約翰現在來，你會對他說些什么？4)Could the dead man have spoken, he would have identified his murderer.如果死人會說話，他會認出誰是謀害他的人。
if引導虛擬條件句用法
1.（表示條件）如果 ，主句用將來時，if從句用現在時表示將來 He will come if you invite him.如果你請他，他會來的.2.（表示虛擬）假如，要是 1）時態：可以表示過去，現在和將來的情況.它的基本特點是時態退后.a.同現在事實相反的假設.句型 ：條件從句 主句 一般過去時 should( would) +動詞原形 If they were here,they would help you.b.表示于過去事實相反的假設.句型：條件從句 主句 過去完成時 should(would) have+ 過去分詞 If she had worked harder,she would have * rice would not have been burnt if you had been more * my lawyer had been here last Saturday,he would have prevented me from * he had come yesterday,I should / would have told him about it.含義：He did not come yesterday,so I did not tell him about * he had not been ill and missed many classes,he would have made greater progress.含義：He was ill and missed many lessons,so he did not make greater progress.c.表示對將來的假想 句型：條件從句 主句 一般過去時 should+ 動詞原形 were+ 不定式 would + 動詞原形 should+ 動詞原形 If you succeeded,everything would be all * you should succeed,everything would be all * you were to succeed,everything would be all right.3.是否 = whether 連接賓語從句 I wonder if she is ill.。
if 虛擬句型
1. （表示條件）如果 ，主句用將來時，if從句用現在時表示將來
He will come if you invite him.
如果你請他，他會來的。
2. （表示虛擬）假如，要是
1）時態：可以表示過去，現在和將來的情況。它的基本特點是時態退后。
a. 同現在事實相反的假設。
句型 ： 條件從句 主句
一般過去時 should( would) +動詞原形
If they were here, they would help you.
b. 表示于過去事實相反的假設。
句型： 條件從句 主句
過去完成時 should(would) have+ 過去分詞
If she had worked harder, she would have succeeded.
The rice would not have been burnt if you had been more careful.
If my lawyer had been here last Saturday, he would have prevented me from going.
If he had come yesterday, I should / would have told him about it.
含義：He did not come yesterday, so I did not tell him about it.
If he had not been ill and missed many classes, he would have made greater progress.
含義： He was ill and missed many lessons, so he did not make greater progress.
c. 表示對將來的假想
句型： 條件從句 主句
一般過去時 should+ 動詞原形
were+ 不定式 would + 動詞原形
should+ 動詞原形
If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right.
3. 是否 = whether 連接賓語從句
I wonder if she is ill.
不知她是否病了。
