、虛擬條件句的三種基本類型：與現在事實相反、與過去事實相反、與將來事實相反。
條件句有真實條件句和非真實(虛擬)條件句兩種。真實條件句所表示的假設是有可能發生的，而非真實條件句則通常表示一種假想，與事實相反或不大可能會發生：
If I have time, I will go with them. 假若我有時間，我就同他們去。(陳述語氣)
If I were you, I would go with them. 假若我是你，我就同他們去。(虛擬語氣)
▲ 與現在事實相反
若與現在事實相反，條件從句的謂語用過去式(be通常用were)，主句謂語用“should (would, could, might)+動詞原形”：
If I knew her number ，I could ring her up. 要是我知道她的電話號碼，我就可以給她打電話了。(可惜我不知道)
▲與過去事實相反
若與過去事實相反，條件從句的謂語用過去完成時(had+過去分詞)，主句謂語用“should (would, could, might)+have+過去分詞”：
If I’d left sooner，I’d have been on time. 要是我早點動身，我就準時到了。(但我動身太遲了)
▲與將來事實相反
若與將來事實相反，條件從句的謂語用過去式(be通常用were)，主句謂語用“should (would, could, might)+動詞原形”：
If I asked him，I’m sure he’d help us. 如果我向他提出要求，肯定他會幫助我們。(不過我不打算這樣做)
注：幾點特別說明
① 主句謂語中的should主要用于第一人稱后。would, might, could的大致區別是：would表示結果，might表示可能性，could表示能力、允許或可能性。比較：
If you tried again ，you would succeed. 要是你再試一試，你就會成功的。(would表結果)
If you tried again， you might succeed. 要是你再試一試，你可能會成功的。(might表可能)
If you tried again ，you could succeed. 要是你再試一試，你就能成功了。(could表能力)
④ 對于與將來事實相反的情形，請注意以下幾點：一是這里說的與將來事實相反，實為對將來情況的推測；二是此用法中的條件從句謂語除用過去式外，有時也用“should+動詞原形”(表示可能性極小，常譯為“萬一”)或“were to+動詞原形”(表示與將來事實相反的假設)；三是當條件從句使用“should+動詞原形”這樣的謂語時，主句謂語除可用“should (would, could, might)+動詞原形”這樣的虛擬語氣外，也可用直陳語氣或祈使語氣：
If it should rain tomorrow, don’t expect me. 萬一明天下雨，就不要等我了。（祈使語氣）
If I should see him, I’ll tell him. 萬一我見到他，我就告訴他。（直陳語氣）
2、錯綜時間虛擬條件句
所謂錯綜時間虛擬條件句即條件從句與主句所指時間不一致，如從句指過去，而主句即指的是現在或將來，此時應根據具體的語境情況，結合上面提到的三種基本類型對時態作相應的調整：
If it had rained last night, the ground would be wet now. 要是昨晚下過雨的話，現在地面就會是濕的。
You would be much better now if you had taken my advice. 假若你當時聽我的話，你現在就會好多了。
3、兩個常考虛擬語氣句型
▲ 句型介紹
這兩個句型是If it weren’t for…和If it hadn’t been for…，這是兩個很常用的虛擬語氣句型，也經常受到命題人的青睞，其意為“若不是(有)”“要不是有”。如：
If it weren’t for water, no plant could grow. 要是沒有水植物就無法生長。
If it hadn’t been for your assistance ，we wouldn’t have succeeded.
=But for your assistance ，we wouldn’t have succeeded.
=Without your assistance ，we wouldn’t have succeeded.
5、wish后賓語從句用虛擬語氣
▲ 用法說明
動詞wish后接賓語從句時，從句謂語要用虛擬語氣。若要表示與現在事實相反的愿望，從句謂語用一般過去時或過去進行時；若表示與過去相反的愿望，從句謂語用過去完成時或would / could+have +過去分詞；若表示將來沒有把握或不太可能實現的愿望，用would (could)＋動詞原形。如：
注：特別注意
從句的時態只與從句所指的時間有關，而與wish的時態無關，比較：
I wish I were rich. 要是我現在有錢就好了。
I wish I had been rich. 要是那時我有錢就好了。
I wished I were rich. 當時我后悔自己沒有錢。
I wished I had been rich. 當時我后悔自己曾經沒有錢。
6、if only后的句子用虛擬語氣
if only 與 I wish一樣，也用于表示與事實相反的愿望，其后所虛擬語氣的時態與 wish后所接時態的情況相同：
If only she had had more courage! 她再勇敢一些就好了。
If only I had listened to my parents! 我要是當時聽了父母的話就好了。
If only she would go with me! 她要是愿意和我一道去就好了!
注：if only 通常獨立使用，沒有主句。
7、as if (though) 從句用虛擬語氣
▲ 基本用法
以as if (as though)引導的方式狀語從句或表語從句，有時用虛擬語氣，若表示與現在事實相反，謂語動詞用一般過去時；若表示與過去事實相反，用過去完成時；表示將來的可能性不大，用would (might, could)+動詞原形：
He acts as if he knew me. 他顯得認識我似的。
They treat me as though I were a stranger. 他們待我如陌生人。
He talks as if he had been abroad. 他說起話來好像曾經出過國。
注：兩點說明
(1) 從句所表示的內容若為事實或可能為事實，也可用陳述語氣：
It looks as if we’ll be late. 我們似乎要遲到了。
(2) 注意 It isn’t as if…的翻譯：
It isn’t as if he were poor. 他不像窮的樣子(或他又不窮)。
8、It’s time后的從句用虛擬語氣
▲ 基本用法
從句謂語通常用過去式表示現在或將來，有時也用過去進行時或“should+動詞原形”(較少見，且should不能省略)，其意為“(早)該干某事了”：
It’s time we went [were going, should go]. 我們該走了。
It’s time I was in bed. 我該上床睡了。(不用were)
9、would rather后句子用虛擬語氣
在would rather, would sooner, would just as soon 后的that從句中, 句子謂語習慣上要用虛擬語氣， 表示”寧愿做什么” ，具體用法為：
▲ 一般過去時表示現在或將來的愿望
I’d rather you went tomorrow (now). 我寧愿你明天(現在)去。
▲ 用過去完成時表過去的愿望
I’d rather you hadn’t said it. 我真希望你沒有這樣說過。
10、賓語從句用虛擬語氣的10種類型
▲ I wish后的賓語從句
動詞wish后接賓語從句時，從句謂語要用虛擬語氣。若要表示與現在事實相反的愿望，從句謂語用一般過去時或過去進行時；若表示與過去相反的愿望，從句謂語用過去完成時或would / could+have +過去分詞；若表示將來沒有把握或不太可能實現的愿望，用would (could)＋動詞原形。如：
I wish I could be of some use. 我希望我能有什么用處。
We wish he didn’t smoke. 我們希望他不吸煙。
I wish prices would come down. 我希望物價能降下來。
▲ 表示“堅持”后的賓語從句
主要是指insist的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
I insisted that he (should) stay. 我堅持要他留下。
注：動詞insist后接賓語從句時，除可用虛擬語氣外，也可用陳述語氣，兩者的區別是：若謂語動詞所表示的動作尚未發生，或尚未成為事實，則用虛擬語氣；若謂語動詞所表示的動作已經發生，或已經成為事實，則要用陳述語氣。比較：
He insisted that I had read his letter. 他堅持說我看過他的信。
He insisted that I should read his letter. 他堅持要我看他的信。
▲ 表示“命令”后的賓語從句
主要是指order, command的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
He ordered that it (should) be sent back. 他命令把它送回去。
▲ 表示“建議”后的賓語從句
主要是指advise, suggest, propose, recommend等的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
He suggested that we should leave early. 他建議我們早點動身。
注：與動詞insist相似，動詞suggest后接賓語從句時，除可用虛擬語氣外，也可用陳述語氣，兩者的區別也是：若謂語動詞所表示的情況尚未成為事實，則用虛擬語氣，此時suggest通常譯為“建議”；若謂語動詞所表示的情況為既成事實，則要用陳述語氣，此時的suggest通常譯為“表明”、“認為”。比較并體會：
He suggested that we (should) stay for dinner. 他建議我們留下吃飯。
I suggested that you had a secret understanding with him. 我覺得你與他心照不宣。
▲ 表示“要求”后的賓語從句
主要是指ask, demand, require, request等后的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
I ask that he leave. 我要求他走開。
He requires that I (should) appear. 他要求我出場。
▲ 表示“提議”“投票”后的賓語從句
主要是指move, vote等后的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
I move that we accept the proposal. 我提議通過這項提案。
▲ 表示“敦促”后的賓語從句
主要是指動詞urge后的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
He urged that they go to Europe. 他敦促他們到歐洲去。
▲ 表示“安排”后的賓語從句
主要是指動詞arrange后的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
He arranged that I should go abroad. 他安排我去國外。
▲ 表示“希望”“打算”后的賓語從句
主要是指動詞desire, intend后的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
She desires that he do it. 她希望他做此事。
▲ 表示“指示”后的賓語從句
主要是指動詞direct后的賓語從句，從句謂語由“should+動詞原形”構成，其中的should在美國英語中通常可以省略。如：
The general directed that the prisoners should be set free. 將軍指示釋放那些俘虜。
11、主語從句中的虛擬語氣
在It is necessary，important，strange，natural， advisable, anxious, compulsory, crucial, desirable, eager, essential, fitting, imperative(絕對必要), impossible, improper, obligatory, possible, preferable, probable, recommended, urgent, vital etc. ；it is a pity；It is requested/suggested/desired/proposed等結構后的主語從句中要用虛擬語氣，即Should+動詞原形或只用動詞原形。如：
▲ It’s important…類
這一類型主要包括It is (was) important (necessary, desirable, imperative, advisable)that. . .句型。如：
It is impossible that he should go home. 他不可能會回家去。
▲ It’s a pity…類
It is a pity that she should fare so badly. 她竟吃得這么差，真可憐。
▲ It’s desired…類
這種主語從句還常用在It is (was) desired (suggested, settled, proposed, requested, decided, etc. ) that...句型。如：
It is requested that a vote be taken. 建議付諸表決。
12、表語從句、同位語從句中的虛擬語氣
在advice, agreement, command, decision, decree, demand, determination, indication, insistence, order, preference, proposal, request, requirement, stipulation ，suggestion， idea，plan，order等名詞后的表語從句、同位語從句中要用虛擬語氣，即should+動詞原形或只用動詞原形。如：
Our suggestion is that you（ should）be the first to go． 我們的建議是你應該第一個去。
13、 在 lest ，for fear that( 以免) , in case (以防)引導的目的狀語從句中的虛擬語氣
在 lest ，for fear that( 以免) , in case (以防)從句中用should＋動詞原形, should 可以省略.
She walked quietly lest she (should) wake up her roommates. 她走得很輕以免吵醒她的室友。

為方便記憶，表格對比
使用虛擬語氣的主要句型 謂語動詞的虛擬形式 例句
表現在的虛擬條件句 從句：用動詞過去（be 多用were ） 1. If I were you, I should study English.
2. I would certainly go if I had time.
主句：would/should/could/might+動詞原形
表過去的虛擬條件句 從句：had + PP 1. If you had taken my advice, you would not have failed in the test.
2. If I had left a little earlier, I would have caught the train.
主句：would/should/could/might +have + PP
表將來的虛擬條件句 從句：①用動詞過去②should +V原③（were +to do ） 1. If it were to rain tomorrow, the meeting would be put off.
2. If you came tomorrow, we would have the meeting.
主句：would/should/could/might +have + PP
省略 if 的條件句 從句：用倒裝形式，即把were,had等置于句首。(并只限were/ had)
主句：根據虛擬的情況采取與從句相應的形式。 1. Were I in school again(= If I were in school again, I would work harder.)
2. Were it not for the rain, (不能說Weren’t it for the rain, ) I would go swimming.
錯綜時間條件句（從句與主句所表示時間不一致） 根據從句與主句表示的不同時進行調整。 1.If you had worked hard yesterday, you would be tired now
2. If we hadn’t been working hard in the past few years, things woud be going so smoothly.
含蓄條件句（虛擬條件暗含在短語或上下文之中，從句不表現出來）(常見有but for“要不是” without等) 根據句子表達的實際情況選用相應的虛擬條件句中的主句的動詞形式 1.Without air, there would be no living things.
2.I would have given you more help, but I was busy now.

名詞性從句中的虛擬語氣
wish, “可惜……”“……就好了”，“悔不該……”“但愿……” wish后從句：與表各種時間的虛擬條件句中的從句動詞形式基本相同。
具體：1，表與現在不能實現的愿望，從句用“過去時，be 用were”
2.表與過去不能實現的愿望，從句用“had+PP 或 could/would +have +PP“
3. .表與將來不能實現的愿望，從句用“could/would +動詞原形”
1.I wish I were a bird.

2. I wish I had known the answer..

would rather 后的賓語從句 would rather后從句：動詞常用過去式 1. I would rather they came tomorrow
demand, insist,suggest, command, order, require, request, desire等一類動詞后的賓語從句
（suggest表“暗示、隱含等”insist表“強調，力言等”不用虛擬語氣。） 從句謂語用“should+動詞原形”，should可省。 1. I suggest you (should)go at once.
2. He suggested that he patient’s leg should be cut and this suggested that he was not good at the case.(注意兩個suggest的準確翻譯)
“It is (was)+上述demand/suggest等動詞過去分詞（或important,natural,strange ,necessary等形容詞）”后的主語從句 從句謂語用“should+動詞原形”，should可省。 1. It ordered that the army (should) get there by 4 a.m.
2. It is necessary that she (should) be sent there at once.
order,suggestion,idea,plan, proposal, advice, demand等名詞后的表語從句或同位語從句 從句謂語用“should+動詞原形”，should可省。 His demand is that we (should )finish the work in 3 hours.
特殊形式的虛擬語氣
as if 引導的從句（表示非真實時）但表真實時，不用虛擬語氣。 與虛擬語氣條件中從句動詞形式基本相同。 1.Tom speaks as if he were a girl.
2.He looks as if he had been to Beijing.
so that, in order that引導的目的狀語從句 May/might/should +V原 I live so that others may live better.
It is (the very/high)time that后的定語從句 從句謂語動詞常用過去式，有時也可用should+動詞原形 It is (high)time that we went (should go) to bed.
It is time that I were leaving.
省去主句的If only(要是……就好了)虛擬條件句 與wish后的賓語從句謂語形式相同。 If only I hadn’t lost the chance!
(= I wish I hadn’t lost the chance)
某些表祝愿的句子 常用原形或“May+動詞原形” Long live world peace!
May you be happy1
表委婉客氣的是常語句 情態動詞的過去式+動詞原形 Could I borrow your bike?
Would you please give me a hand?
虛擬語氣的用法
虛擬語氣表示一種假設的情況，或一種主觀的愿望，即動詞所表示的動作或狀態并非事實，或不可能實現。英語虛擬語氣的形式有下列幾種：
一、與現在事實相反
連接詞 條件從句 結果從句
If 1.動詞過去式(或were)
2.助動詞（過去式）+動詞原形 Should
Would +動詞原形
could
might
If had the time, John would make a trip to China to see the Great Wall.
If I were you, I would give up drinking immediately.
二.與將來事實相反
連接詞 條件從句 結果從句
If 1. should+動詞原形
2. 動詞過去式
3、were to+動詞原形 Should
Would +動詞原形
could
might
If you should lose, what would you do?
If I were to see her tomorrow, I would tell her thetruth.
If you went there next time, you would see what I mean.
三、與過去事實相反
連接詞 條件從句 結果從句
If had+過去分詞 Should
Would + have+過去分詞
could
might
If I’d dnown that it was going to rain, I would never have gone for a walk in the country.
四、虛擬語氣的幾種特殊用法
省掉if的條件從句結構：
Had you asked me, I would have told you. (=If you had asked me,…)
2.有時虛擬條件不用條件從句而用不定式、分詞、介詞、名詞、連接詞或定語從句來表示，如：
A true friend would not do such a thing.
(=If he were a true friend, he...)

(=If there were no water,…)

(=If you hadn’t helped me,…)
3. 有時條件從句中的動作和結果從句中的動作發生的時間不一致，如：
If he had followed the doctor’s advice, he would be quite all right now.
If I were you, I would have gone home.
五、虛擬語氣的其他用法
1、Suggest, advise 等動詞之后賓語從句須用虛擬語氣，其句子結構如下：
suggest, advise, recommend, demand,
require, insist, urge, request, order, +that…(should )+動詞原形
devide, ask, move, propose等
注意：在此結構中that不可省略；should省不省均可。
He suggested that they (should ) stop smoking.
上述動詞的名詞形式出現時，that 引導的從句仍用虛擬語氣。
He made a request that they (should ) stop smoking.
如果that 引導的從句所表達的內容是事實，也可用陳述語氣。
He insists that he is right.
2、It is (was )+necessary, a pity 等+that引導的從句須用虛擬語氣，其句子結構如下：
imperative, advisable, 動詞完成式
It is (was) + important,natural, necessary, +that…(should) +
essential, strange,等 動詞原形
It is important that you (should) follow the doctor’s orders.
It is right that you should have done your homework.
3、wish的用法
動詞過去式或were—與現在事實相反
主語+wish(that)+主語 + 動詞過去完成式—與過去事實相反
助動詞過去試+動詞原形—與將來事實相反
I wish I were a pop singer. (=I am sorry I am not a pop singer..)
I wish I had never stopped teaching. (=I am sorry I stopped teaching.)
I wish they’d let us get some sleep.
注意：wish與hope接賓語從句的區別在于：hope表示一般可以實現的希望，賓語從句用陳述語氣。wish表示很難或不大可能實現的希望,賓語從句用虛擬語氣。試比較：
（1） We hope they will come,(We don’t know if they can come.)
（2） We wish they could come,(We know they are not coming.)
4、as if, as though, would(had) rather(that)引導的從句須用虛擬語氣，如：
He acts as if nothing had happened.
I would rather you didn’t tell him.
5、It’s (high) time that…+動詞過去式或should+動詞原形，如：
It’s time (that) you had a hair cut.
It’s high time (that) we took some action.

虛擬語氣用來表示假想，而不表示客觀存在的事實，所說的是一個條件，不一定是事實，或與事實相反。虛擬語氣通過謂語動詞的特殊形式來表示。
英語中的語氣分為陳述語氣、祈使語氣、虛擬語氣三類。虛擬語氣表示說話者做出的假設并非事實，或難以實現的，甚至表達相反的概念。另外表示主觀愿望或表達某種強烈的感情時，也用虛擬語氣。
一、陳述語氣：表示動作或狀態是客觀存在的、確定的或符合事實的，用于陳述句、疑問句和某些感嘆句中。如:Who was it that they want to help?他們想要幫忙的人到底是誰呀?
二、、祈使語氣：表示說話人對對方的請求、警告，建議或命令。如:Never be late again! 再也不要遲到了。
三、條件狀語從句中的應用：條件句可分為兩類，一類為真實條件句，一類為非真實條件句。非真實條件句表示的是假設或實際可能性不大的甚至完全不可能發生的情況，故采用虛擬語氣。如：
If he is free，he will ask me to tell stories.如果他有空，他會要求我講故事。
If I were you，I would go at once.如果我是你，我馬上就會去。
1、表示與現在事實相反的情況
從句:If+主語+動詞一般過去時(Be動詞用were)
主句:主語+ should/would/might/could+do:
If I were you，I would take an umbrella.
如果我是你，我會帶把傘。(事實:我不可能是你)
2、表示與過去事實相反的情況
從句:If+主語+had+done
主句:主語+should/would/might/could+have done
If I had got there earlier，I should/would have met her.
如果我早到那兒，我就會見到她。
(事實:去晚了)
3、表示與將來事實相反
從句:①if+主語+were to do
②if+主語+should+do
③if+主語+動詞一般過去式(be動詞用were)
主句:主語+should/would/might/could+do
如果下周日下大雪，我們就去滑冰。(事實:下雪可能性很小，不可能)
If she were to be here next Monday，I would tell her about the matter.

日語中表達客觀存在用現在時態。

第一個問題回答：在從句中，主句用的是一般過去時，那從句中的“客觀存在的真理”的謂語動詞還是用一般現在時。特殊情況特殊對待，例如My son asked the teacher if the earth went round the sun.
例句回答：is

客觀存在的真理用一般現在時
如：eg. The earth moves round the sun. 地球繞著太陽轉。
The sun rises in the east and sets in the west. 太陽東升西落。
Two and two makes four. 二加二等于四。
Seeing is believing. 眼見為實。

個人認為你給的句子中不是客觀真理，應填was

一般現在時
3）表達客觀真理，格言警句或事實
eg. The earth moves round the sun. 地球繞著太陽轉。
The sun rises in the east and sets in the west. 太陽東升西落。
Two and two makes four. 二加二等于四。
Seeing is believing. 眼見為實。

1． 動詞構成：謂語動詞使用動詞原形；系動詞為am, is, are 的形式。
主語是第三人稱單數時，謂語動詞需有變化：
1）直接加 “s”；
gives takes asks
2）以輔音字母加“y”結尾的動詞，變“y”為“i”，再加“es”；
carry – carries
3）以“o, s, x, ch, sh,”結尾的動詞加“es”。
goes dresses watches brushes
2． 功能：1）表達習慣性，規律性的動作
eg. I never get up early on Sundays. 星期天我從來都不早起。
I sometimes stay in bed until lunchtime. 有時候我一直躺倒吃午飯的時間。
2）表達現在的事實狀態或動作
eg. We all like football. 我們都喜歡足球。
Birds fly. 鳥會飛。
This picture is of great value. 這幅畫具有極大的價值。
3）表達客觀真理，格言警句或事實
eg. The earth moves round the sun. 地球繞著太陽轉。
The sun rises in the east and sets in the west. 太陽東升西落。
Two and two makes four. 二加二等于四。
Seeing is believing. 眼見為實。
3． 經常搭配的副詞：
often sometimes usually always
every year seldom occasionally frequently
副詞的位置：通常放在實義動詞之前，助動詞之后。
eg. He doesn’t always come by train. 他不總是坐火車來。
Do you ever read in bed? 你在床上躺著看過書嗎？
I never like jazz. 我從來都不喜歡爵士樂。
He rarely gets up before 10 o’clock. 在10點之前他很少起床。
We frequently have lunch at this restaurant. 我們總在這家餐館吃飯。

填is吧

賓語從句表示的是現階段存在的客觀事實時用
一般現在時。