、表示与现在事实相反的情况：
从句：If 主语+过去时(Be动词用were)
主句：主语+should/would/could/might+do：
1．If I were you,I would take an umbrella.
如果我是你，我会带把伞。（事实：我不可能是你）
2．If I knew his telephone number,I would tell you.
如果我知道他的电话号码，我就会告诉你。（事实：不知道）
3．If there were no air or water,there would be no living things
on the earth.
如果没有水和空气，地球上就不会有生物。(事实：地球上既有空气也有水)
4．If I had any money with me,I could lend you some.
如果我带钱了，我就会借给你些。（事实：没有带钱）
5．If he studied harder,he might pass the exam.
如果他再努力些，就能通过考试了。（事实：没有努力）
6．she looked at me
as if I had been a stranger.
她看我的样子好像我是一个陌生人。（事实：我并非陌生人）
7．If I were you, I'd wear a shirt and tie.
如果我是你，我就会穿衬衫和领带。(事实：我并不是你）
2、表示与过去事实相反的情况
从句：If 主语+had+done
主句：主语+should/would/could/might+have done
eg：
1． If I had got there earlier,I should/could have met her.
如果我早到那儿，我就会见到她。
（事实：去晚了）
2．If he had taken my advice,he would not have made such a
mistake. 如果他听我的劝告的话，就不会犯这样的错误了。
（事实：没有听我的话）
3、表示对将来情况的主观推测
从句：①if+主语+were to do
②if+主语+should/would/could/might+do
③if+主语+did（动词
过去式）/were
主句：主语+should/would/could/might+do
eg：
1．If he should come here tomorrow,I would talk to him.
如果他明天来这儿的话，我就跟他谈谈。（事实：来的可能性很小）
2．If there were a heavy snow next Sunday,we would not go
skating.
如果下周日下大雪，我们就不能去滑冰了。（事实：下雪可能性很小）
3．If she were to be here next Monday,I would tell her about the
matter.
如果她下周一来这儿的话，我就会告诉她这件事的始末。（事实：来的可能性很小）
4、 有时，虚拟条件句中，结果主句和条件从句的谓语动作若不是同时发生时，
虚拟语气的形式应作相应的调整。这种条件句叫错综条件句。
①从句的动作与过去事实相反，而主句的动作与现在或现在正在发生的事实不符。
eg：
If I had worked hard at school,I would be an engineer,too.
如果我在学校学习刻苦的话，我现在也会成为一个工程师了
If they had informed us,we would not come here now.
如果他们通知过我们的话，我们现在就不会来这里了。
②从句的动作与现在事实相反，而主句的动作与过去事实不符。
如：
If he were free today,we would have sent him to Beijing.
如果他今天有空的话，我们会已经派他去北京了。
If he knew her,he would have greeted her.
要是他认识她的话，他肯定会去问候她了。
5、 当虚拟条件句的
谓语动词含有were,should,had时，if可以省略，这时条件从句要用倒装语序，即把were,should,had等词置于句首，这种多用于书面语。eg：
Should he agree to go there,we would send him there.
要是他答应去的话，我们就派他去。
Were she here,she would agree with us.
如果她在这儿的话，她会同意我们的。
Had he learnt about computers,we would have hired him to work
here.
如果他懂一些电脑知识的话，我们已经聘用他来这里工作了。
6、非真实条件句中的条件从句有时不表达出来，只暗含在副词、
介词短语、上下文或其他方式表示出来，这种句子叫做含蓄条件句，在多数情况下，条件会暗含在短语中，如without…，but for…等
eg：
But for his help,we would be working now.
要不是他的帮助，我们还会在工作呢。
Without your instruction,I would not have made such great
progress.
要是没有你的指导，我不会取得如此大的进步。
We didn't know his telephone number,otherwise we would have
telephoned him.
我们不知道他的电话号码，否则我们就会给他打电话。
7、 有时，虚拟条件句中，主、从句可以省略其中的一个，来表示说话人的一种强烈的感情。
①省略从句
He would have finished it. 他本该完成了。
You could have passed this exam. 你本能通过这次考试的。
②省略主句
If I were at home now. 要是我现在在家里该多好啊。
If only I had got it. 要是只有我得到它了该多好啊。
8.注意，在虚拟语气的从句中，动词be的过去时态一律用were，不用was。
eg：If I were you,I would go to look for him.
如果我是你，就会去找他。
目的状语从句
1、在for fear that,in
case,lest引导的从句中，若用虚拟语气时，从句谓语为：should + do。并且 should能省略
She examined the door again for fear that a thief (should) come
in.
她又把门检查了一遍，以防盗贼的进入。
He started out earlier lest he (should) be late.
他早早的就出发了以防迟到。
2、在so that,in order that
所引导的目的状语从句中，从句中的谓语为：can / could / may / might / will / would /
should + do 。
He goes closer to the speaker so that he can hear him clearer.
他走近说话的人以便能听得更清楚。
He read the letter carefully in order that he should not miss a
word. 他把信读得很仔细以便不漏掉一个字。
宾语从句
[1]一、I
wish后的宾语从句
动词wish后接宾语从句时，从句谓语要用虚拟语气。若要表示与现在事实相反的愿望，从句谓语用
一般过去时或过去进行时；若表示与过去相反的愿望，从句谓语用
过去完成时或would
/ could+have +
过去分词；若表示将来没有把握或不太可能实现的愿望，用would (could)+动词原形。如：
I wish I could be of some use. 我希望我能有什么用处。
We wish he didn’t smoke. 我们希望他不吸烟。
I wish prices would come down. 我希望物价能降下来。
I wish the train would come. 我希望火车会来。
二、表示“坚持”后的宾语从句
主要是指insist的宾语从句，从句谓语由“should+动词原形”构成，其中的should在
美国英语中通常可以省略。如：
I insisted that he (should) stay. 我坚持要他留下。
He insisted that I (should) go with them. 他坚持要我同他们一起去。
Rose insisted that he be present. 罗斯坚持要他出席。
The detective insisted that he should have a look.
警探坚持要查看。
注意：动词insist后接宾语从句时，除可用虚拟语气外，也可用陈述语气，两者的区别是：若谓语动词所表示的动作尚未发生，或尚未成为事实，则用虚拟语气；若谓语动词所表示的动作已经发生，或已经成为事实，则要用陈述语气。比较：
He insisted that I had read his letter. 他坚持说我看过他的信。
He insisted that I should read his letter. 他坚持要我看他的信。
三、表示“命令”后的宾语从句
主要是指order,
command的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
He ordered that it (should) be sent back. 他命令把它送回去。
Thejudge ordered that the prisoner should be remanded.
法官命令被告还押。
The King ordered that the man be released. 国王命令释放那人。
He commanded that we (should) attack at once. 他命令我们立即发起进攻。
四、表示“建议”后的宾语从句
主要是指advise, suggest, propose,
recommend等的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
He suggested that we should leave early. 他建议我们早点动身。
The doctor advised that he change his job. 医生劝他换工作。
They recommend that this tax be abolished. 他们建议取消这种税。
I suggest that we (should) have lunch right now.
我建议我们现在就吃午饭。
The committee proposed (that)
Mr. Day be elected.
委员会建议推选戴先生。
The doctor advised [suggested] that he (should) not smoke.
医生建议他不要抽烟。
I propose that the matter be put to the vote at once.
我提议对此问题立刻进行表决。
He proposed that Mr. O’Leary be the chairman.
他提议奥列利先生担任主席。
She suggested that I (should) be responsible for the
arrangements. 她建议我来负责进行安排。
注意：与动词insist相似，动词suggest后接宾语从句时，除可用虚拟语气外，也可用陈述语气，两者的区别也是：若谓语动词所表示的情况尚未成为事实，则用虚拟语气，此时suggest通常译为“建议”；若谓语动词所表示的情况为既成事实，则要用陈述语气，此时的suggest通常译为“表明”、“认为”。比较并体会：
He suggested that we (should) stay for dinner. 他建议我们留下吃饭。
What he said suggested that he was a cheat. 他说的话表明他是个骗子。
I suggested that you had a secret understanding with him.
我觉得你与他心照不宣。
五、表示“要求”后的宾语从句
主要是指ask, demand, require,
request等后的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
I ask that he leave. 我要求他走开。
He requires that I (should) appear. 他要求我出场。
They require that I go at once. 他们要求我立刻走。
I demand that John (should) go there at once. 我要求约翰立即到那里去。
I requested that he should use his in fluence on my behalf.
我请求他为我施用他的影响。
The asked that the message be given to Madame immediately.
他要求把信息立即带给夫人。
They demanded that the right to vote be given to every adult
man. 他们要求给予每个成年男子以选举权。
六、表示“提议”“投票”后的宾语从句
主要是指move,
vote等后的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
I move that we accept the proposal. 我提议通过这项提案。
Mr. Chairman, I beg to move that the meeting be adjourned.
主席先生，我提议休会。
Congress has voted that the present law be maintained.
国会投票决定维持现在这条法律。
Claudel moved that Norwood should be made a member of the
committee. 克洛戴尔提出动议，让诺伍德当一名委员。
七、表示“敦促”后的宾语从句
主要是指动词urge后的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
He urges that the restrictions be lifted. 他敦促取消这些限制。
He urged that they go to Europe. 他敦促他们到欧洲去。
He urged that the rates should be reduced. 他敦请减轻捐税。
He urged that the matter should go to arbitration.
他极力主张这件事要提交仲裁。
They urged that relief work should be given priority.
他们敦促将救济工作放在优先位置。
八、表示“安排”后的宾语从句
主要是指动词arrange后的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
He arranged that I should go abroad. 他安排我去国外。
I arranged that Tom should meet them. 我安排好叫汤姆去接他们。
They arranged that the minister should be met at the airport.
他们安排在机场迎接这位部长。
It was arranged that they should leave the following spring.
已安排好他们第二年春天离开。
They’ve arranged that I should absent myself for part of the
meeting. 他们安排好让我一部分时间不在开会现场。
九、表示“希望”“打算”后的宾语从句
主要是指动词desire,
intend后的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
She desires that he do it. 她希望他做此事。
They intended that the news (should) be suppressed.
他们打算封锁这条消息。
I desire the patient should have a bath every day.
我希望病人每天洗澡。
十、表示“指示”后的宾语从句
主要是指动词direct后的宾语从句，从句谓语由“should+动词原形”构成，其中的should在美国英语中通常可以省略。如：
The general directed that the prisoners should be set free.
将军指示释放那些俘虏。
其他用法
1、一想要( desire ) 一宁愿( prefer ) 一坚持( insist
)二命令( order , command ) 三建议( advise , suggest ,
propose/recommend) 四要求( demand , require , request ,
ask)中，无论主句谓语动词为何种时态，从句的谓语动词都用："should + do"。should可以省略。
eg：He suggested that we (should) take the teacher's
advice.
He insisted that we (should) take the teacher's advice.
He demand that we (should) take the teacher's advice.
He ordered that we (should) take the teacher's advice.
insist 意为“坚持某种动作”才用虚拟语气；意为“坚持某种观点，某个事实”则不用虚拟语气。
eg：
He insists he is a student.
他坚持说他是个学生。
这个语句表示的是事实，因此在这个语句中不能使用虚拟语气。
suggest意为“建议”才用虚拟语气，意为“暗示”则不用虚拟语气。
eg：
His face suggests that he looks worried .
他的表情暗含着他很担心。
这个句子本身是事实，因此它就没有用到虚拟语气。
2、表情绪.观点的形容词或名词也要用虚拟语气.如：necessary、important、impossible、natural、strange、surprising、funny、right、wrong、better、a
pity ,the shame ,no wonder等。
句型：It is.......that +主语从句，从句的谓语动词都要用
should+原型或 只用动词原型。
eg:
Do you think it is necessary that he (should)not be sent to
Lingbao.
It is strange that such a person should be our friend.
奇怪的是这样一个人会成为我们的朋友。
注：这一点还没有准确的说法，希望善心人能把这点补充完全。
3、 在even if,even though 所引导的让步状语从句中用may/might+动词原形，may/might可以省略，表示与现在相反的情况；从句用过去完成时，表示与过去相反的情况，类似的词有though/even though/whatever/however/so
long as; 主句、从句的结构与if所引导的条件从句结构相同。
eg：
Even if he were here himself,he should not know what to
do.
即使他亲自来也不知该怎么办。（事实：他没来）
Nobody could save him even though Hua Tuo should come here.
即使华佗在世也救不了他。（事实：华佗不在世）
4、 在whatever，whichever，whenever，whoever,wherever，however,no
matter wh-等引导的让步状语从句中，从句虚拟语气结构为：
指现在或将来：may +do。
eg：
We will finish it on time no matter what may happen.
不管发生什么事，我们都要按时完成。
We will find him wherever he may be.
无论他在哪里，我们都要找到他。
I will wait for him no matter how late he may come.
不管他来的多么晚，我都会等他。
指过去：may +have done 。
eg：
You mustn't be proud whatever great progress you may have made.
不管你取得了多么大的进步，你也不能骄傲。
We must respect him no matter what mistakes he may have made.
不管他犯过什么错误，我们必须尊敬他。
5、一般would rather,had rather,would sooner等之后的宾语从句常表示与客观事实不相符的一种愿望，故使用虚拟语气。其虚拟语气的结构为：
过去 had + done
现在 过去时(be 用were )
将来 过去时(be 用were ) （would rather 将来情况用一般过去时）
eg：
I'd rather you had seen the film yesterday.
我倒想你昨天看过了这场电影。
I'd rather you were here now.
我倒想你现在在这儿。
We'd rather you went here tomorrow.
我们倒想你明天去那儿
注：注意would rather，had rather，would sooner的细微差别，可以百度一下查查。
6、虚拟语气还可用在定语从句中，表示：“早该做某事了”时，定语从句中的谓语动词须用虚拟语气，其虚拟语气的结构为：It is
(high / about) time that + 主语+ 动词的过去式/ should + do（优先使用动词过去式）
，即从句用虚拟过去式。
It is time that I went to pick up my daughter at school.
我该去学校接我的女儿了。
It is high time you should go to work.
你早该上班了。
7、 简单句中的虚拟语气
（1） 说话时，为了表示客气、谦虚、委婉而有礼貌，言语常使用虚拟语气。其虚拟语气的结构形式常为：would / could
/ might / should +do。
eg：
Would you mind me shutting the door?
你介意我把门关起来吗？
You should always learn this lesson by heart.
你要把这个教训牢记于心。
I should agree with you.
我本该同意你的观点。（委婉的不同意）
（2）表示“祝愿”时，常用may + 主语+ do。
eg：
May you have a good journey!
祝你一路顺风。
May your youth last forever!
祝你青春永驻。
（3）表示强烈的“愿望”、“祝愿”时，常用do。
eg：God bless us. 上帝保佑。
（4）习惯表达中常用的虚拟语气。
① 提出请求或邀请。eg：
Would you like to have a talk with us this evening?
今天晚上来跟我们聊天好吗？
Could I use your bike now?
我可以用一下你的单车吗？
② 陈述自己的观点或看法。eg：I should be glad to meet you. 见到你我会很高兴。I would try my best to help you. 我会尽力帮助你。③提出劝告或建议。eg：You'd better ask your father first. 你最好先问一问你的父亲。You should make a full investigation of it first. 你应该先全面调查一番。④ 提出问题。eg：Do you think he could get here on time你认为他能按时来吗？Do you expect he would tell us the truth? 你期望他会告诉我们真相吗？