虚拟语气的概念：

虚拟语气用来表示说话人的主观愿望或假想，所说的是一个条件，不一定是事实，或与事实相反。在条件句中的应用条件句可分为两类，一类为真实条件句，一类为非真实条件句。非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。

1、虚拟语气在条件句中的用法： 　　
条件句有真实条件句和虚拟条件句两种。真实条件句所表示的假设是有可能发生的，此时主句
不用虚拟语气；而虚拟条件句则表示一种假想，与事实相反或不大可能会发生，此时用虚拟语气。
如：If I have time, I will go. 假若我有时间，我就去。（陈述语气）
    If I were you, I would go. 假若我是你，我就去。（虚拟语气）

时态类型	主句谓语形式	条件句的谓语形式	例句
与现在事实相反	would/should/could/ might+ V原	动词过去式did be 多用were	1. If I were you, I should study English. 2. I would certainly go if I had time.
与过去事实相反	would/should/could/ might + have done	动词过去完成式 had done	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.
与将来事实相反	would/should/could/ might + V原	①动词过去式 ②should +V原 ③were + to do	1. If you came tomorrow, we would have the meeting. 2. If it were to rain tomorrow, the meeting would be put off.
规律总结：从句都往过去推一个时态，如：与现在相反的if从句就用过去时；与过去相反用过去完成时（即过去的过去）

注意：　　
1）I would/should/could/might主句谓语中的should主要用于第一人称后；would表示结果还
   表示过去经常常常做某事，might表示可能性，could表示能力、允许或可能性。比较： 　　
  If you tried again , you would succeed. 要是你再试一试，你就会成功的。 (would表结果) 　　
  If you tried again, you might succeed. 要是你再试一试，你可能会成功的。 (might表可能) 　　
  If you tried again, you could succeed. 要是你再试一试，你就能成功了。(could表能力) 　　
2）错综时间虚拟条件句 即条件从句与主句所指时间不一致，如从句指过去，而主句即指的是现在
   或将来，此时应根据具体的语境情况，结合上面提到的三种基本类型对时态作相应的调整： 　　
   If it had rained last night, the ground would be wet now.
   要是昨晚下过雨的话，现在地面就会是湿的。 　　  
   You would be much better now if you had taken my advice.
   假若你当时听我的话，你现在就会好多了。 　　
3）If虚拟条件句的否定（含蓄条件句） 常考两个句型：If it weren’t for…和If it hadn’t
   been for…，其意为“若不是(有)” “要不是”。如： 　　
   If it weren’t for water, no plant could grow. 要是没有水植物就无法生长。 　　
   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. 　　
4）If虚拟条件句的倒装形式，即把were, had, should置于句首。例： 　　
   Were I in school again (= If I were in school again), I would work harder. 　　
   Had you asked me, I would have told you. (=If you had asked me,…)
2、使用虚拟语气的常见结构或从句：
1）wish与hope接宾语从句的区别在于：hope表示一般可以实现的希望，宾语从句用陈述语气。
   wish表示很难或不大可能实现的希望,宾语从句用虚拟语气。试比较： 　　
（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.) 　　
2）if only 与 I wish一样，也用于表示与事实相反的愿望，其后所虚拟语气的时态与 wish后
   所接时态的情况相同： 　　
   If only she had had more courage! 她再勇敢一些就好了。 　　
   If only I had listened to my parents! 我要是当时听了父母的话就好了。 　　
   If only she would go with me! 她要是愿意和我一道去就好了! 　　
注意：if only 通常独立使用，没有主句。 　　
3）I would rather后句子用虚拟语气只分现在和过去.在would rather, would sooner, would
   just as soon后的that从句中, 句子谓语习惯上要用虚拟语气，表示“宁愿做什么”，具体用法为： 　　
①一般过去时表示现在或将来的愿望 　　
  I’d rather you went tomorrow (now). 我宁愿你明天(现在)去。 　　
②用过去完成时表过去的愿望 　　
  I’d rather you hadn’t said it. 我真希望你没有这样说过。 　　
4）as if (though) 从句用虚拟语气。以as if (as though)引导的方式状语从句或表语从句，
   有时用虚拟语气，则与wish用法相同，例： 　　
   He acts as if he knew me. 他显得认识我似的。 　　
   They treat me as though I were a stranger. 他们待我如陌生人。 　　
   He talks as if he had been abroad. 他说起话来好像曾经出过国。 　　
注意： 　　
（1）从句所表示的内容若为事实或可能为事实，也可用陈述语气： 　　
     It looks as if we'll be late. 我们似乎要迟到了。 　　
（2）注意 It isn't as if…的翻译： 　
　  It isn't as if he were poor. 他不像穷的样子(或他又不穷)。
3、从句中should+动词原形，should可省略 　　
1）在 lest ，for fear that (以免), in case (以防) 引导的目的状语从句中的虚拟语气 　　
   She walked quietly lest she (should) wake up her roommates. 她走得很轻以免吵醒她的室友。 　　
2）表应当做 值得做 一类动词后的宾语从句 　　
   建议advise, suggest, propose, recommend
   命令order, command 　　
   请求ask, demand, require, request
   指示direct 　　
   敦促urge
   提议move, vote 　　
   希望desire
   坚持insist 　　
   打算intend
   安排 arrange 　　
例如： 　　
   I insisted that he (should)stay. 我坚持要他留下。 　　
   He urged that they go to Europe. 他敦促他们到欧洲去。 　　
   He suggested that we shouldleave early. 他建议我们早点动身。 　　
   He ordered that it (should) be sent back. 他命令把它送回去。 　　
   I ask that he leave. 我要求他走开。 　　
   He requires that I (should) appear. 他要求我出场。 　　
   I move that we accept the proposal. 我提议通过这项提案。 　　
   He arranged that I should go abroad. 他安排我去国外。 　　
   She desires that he do it. 她希望他做此事。 　　
   The general directed that the prisoners should be set free. 将军指示释放那些俘虏。 　　
注意：suggest表“暗示”insist表“坚持认为”不用虚拟语气 　　
比较：Heinsistedthat Ihad readhis letter. 他坚持说我看过他的信。 　　
      Heinsistedthat I should readhis letter. 他坚持要我看他的信。 　　
      Hesuggestedthat we (should) stayfor dinner. 他建议我们留下吃饭。 　　
      I suggested that you had a secretunderstanding with him. 我觉得你与他心照不宣。 　　
3）order, suggestion, idea, plan, proposal, advice, demand等名词后的表语从句或同位语从句 　　 
   Oursuggestionis that you (should) be the first to go. 我们的建议是你应该第一个去。 　　
4）advice, agreement, command, decision, decree, demand, determination, indication,
   insistence, order, preference, proposal, request, requirement, stipulation, suggestion,
   idea, plan, order“It is (was)+ 紧急 重要-带感情色彩上demand/suggest等动词过去分词或
   important,natural,strange ,necessary，surprised, appropriate等形容词后的主语从句 　　
（1） It is ordered that the army (should)get there by 4 a.m. 　　
（2） It is necessary that she (should) besent there at once. 　　
注意：It is necessary, important, strange, natural, advisable, anxious, compulsory,
      crucial, desirable, eager, essential, fitting, imperative (绝对必要), impossible,
      improper, obligatory, possible, preferable, probable, recommended, urgent, vital
      etc.; it is a pity；It is requested/suggested/desired/proposed
4、It's time后的从句用虚拟语气 　　
   从句谓语通常用过去式表示 (早)该干某事了有时也用过去进行时或“should+动词原形” (较少见，
   且should不能省略) 　　
   It's time we went [were going, should go]. 我们该走了。 　　
   It's time I was in bed. 我该上床睡了。(不用were) 　　
   It's time = It is (the very/high/right/about) time　
5、wish和as if引导的虚拟
1）表示与现在事实相反的愿望
　 构成：主语 + wish (that) + 从句主语 + 动词过去式 （be 一律用were） 　　
   例如：
   I wish I knew everything in the world. 　　
   I wish that the experiment were a success. 　　
   We wish we had wings.
2）表示与过去事实相反的愿望
　 构成：主语 + wish (that) + 从句主语 + would/could + have + 过去分词或had + 过去分词 　　
   例如：
   I wish that you had called yesterday. 　　
   I wish that I could have gone with you last night. 　　
   I didn’t go to the party, but I do wish I had been there.
3）表示将来不大可能实现的愿望
　 构成：主语 + wish (that) + 从句主语 + would/should/could/might + 原形动词 　　
   例如：
   I wish that he could try again. 　　
   I wish that someday I should live on the moon. 　　
   We wish that they would come soon.
4）As if 表好像……我们经常会利用一下句型来表达不能实现的虚拟状态：It is as if……。
   (就好象是……) 　　As if + 从句+主句。（好像…… Sb.+ do…）表达一种假设的条件。
    而As if之后的假设内容的语法结构和wish虚拟的结构一样。
5、使用虚拟条件句时要注意的几点：
1）当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，被称为“错综时间条件
   句”，动词的形式要根据它所表示的时间作出相应的调整。如： 　　
   If you had followed my advice just now, you would be better now. 　　
   If you had studied hard before, you would be a college student now, and you would
   graduate from a college in four years’ time. 　　
2）if 省略句 　　
   在条件句中可省略if, 把were, had, should提到句首，变为倒装句式。如： 　　
   If I were at school again, I would study harder.
   → Were I at school again, I would study harder. 　　
   If you had come earlier, you would catch the bus.
   → Had you come earlier, you would catch the bus. 　　
   If it should rain tomorrow, we would not go climbing.
   → Should it rain tomorrow, we would not go climbing. 　　
注意：若省略的条件句中的谓语动词是否定形式时，不能用动词的缩略形式。如：我们可以说：
      Were it not for the expense, I would go abroad now. 但不能说：Weren't it for
      the expense, I would go abroad now. 　　
3）用介词短语代替条件状语从句。常用的介词有with, without, but for。如： 　　
   What would you do with a million dollars? (= if you had a million dollars) 　　
   We couldn't have finished the work ahead of time without your help.
   (= if we hadn't got your help) 　　
   But for the rain (= If it hadn't been for the rain), we would have finished the work. 　　
4）含蓄条件句 　　
   有时为了表达的需要，在虚拟语气中并不总是出现if引导的条件句，而通过其他手段来代替条件句。 　　
   I was ill that day. Otherwise, I would have taken part in the sports meet. (副词) 　　
   He telephoned to inform me of your birthday, or I would have known nothing about it. (连词) 　　
   A man who stopped drinking water would be dead in about seven days. （定语从句） 　　
   I might have given you more help, but I was too busy. (连词) 　　
   Everything taken into consideration, they would have raiser their output quickly. (独立主格结构)
（1）混合型虚拟语气：当虚拟条件从句与结果主语所表达的时间不一致时，被称为“混合条件句”，
     这种虚拟语气被称为“混合型虚拟语气”，动词的形式要根据它所表达的时间作相应调整。如： 　　
     If you had followedthe doctor's advice ,he would be all right now.
    (条件从句表达的时间是过去，因此用had+过去分词；主句表示的时间是现在，因此用would+动词原形) 　　
（2）含蓄型虚拟语气：有时候，虚拟条件不是通过if引导的条件句来表示，而是暗含在上下文中 　　
     ①用but for 、without(如果没有）等来代替条件从句，如 　　
     Without electricity human life would be quite different
     =If there were no electricity, human life would be quite different 　　
     ②用otherwise、or(or else),even though等表示与上文的情况相反，从而引出虚拟语气。如： 　　
     I lost your address.Otherwise,I would have visited you long before.
     =I lost your address.If I hadn't lost your address ,I would have visited you long before. 　　
（3）虚拟条件通过but暗示出来。如： 　　
     He would have given you more help,but he was too busy. 　　
     他本来会给你更多的帮助，但是他太忙了。也就是说，如果那时他不忙，他可以给你更多的帮助。   
     句中but he was too busy实际上暗示了一个虚拟条件——如果那时他不忙。 　　
     He would lose weight, but he eats too much. 　　
     他本来可以减肥的，但是他吃的太多了。也就是说，如果他吃得不多的话，他是可以减肥的。句
     中的but he eats too much实际上暗示了一个虚拟条件——如果他吃得不多。

虚拟语气知识体系：

	条件从句中的谓语动词形式	主句中的谓语动词形式
与过去事实相反	had+过去分词	should/would+have+过去分词
与现在事实相反	过去式	should/would+动词原形
与将来事实相反	1、过去式	should/would+动词原形
	2、should+动词原形	should/would+动词原形
	3、were to+动词原形	should/would+动词原形

虚拟语气在条件句中的应用：

一、真实条件句：
真实条件句真实条件句用于陈述语气，假设的情况可能发生，其中if是如果的意思。
时态关系句型：条件从句：一般现在时；主句：shall/will+动词原形
如：If he comes, he will bring his violin.
典型例题：
The volleyball match will be put off if it___.
A. will rain
B. rains
C. rained
D. is rained
答案：B。真实条件句主句为将来时，从句用一般现在时。
注意：1）在真实条件句中，主句不能用be going to表示将来，该用shall, will。
如： （错） If you leave now, you are never going to regret it. 
         （对） If you leave now, you will never regret it.
            2）表示真理时，主句谓语动词便不用shall(will)+动词原形，而直接用一般现在时的动词形式。

二、非真实条件句：
非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。 
1）时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。
a. 同现在事实相反的假设。
句型：从句：一般过去时；主句：should(would)+动词原形
如：If they were here, they would help you.
b.表示于过去事实相反的假设。
句型：条件从句：过去完成时；主句：should(would)have+过去分词
如：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.
c.表示对将来的假想句型：
条件从句：一般过去时；主句：should+动词原形
                   从句： were+不定式；主句：would+动词原形 should+动词原形
如：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.

三、混合条件句：
主句与从句的动作发生在不同的时间，这时主，从句谓语动词的虚拟语气形式因时间不同而不同，这叫做混合条件句。
如：If you had asked him yesterday, you would know what to do now. （从句与过去事实相反，主句与现在事实相反。）
        If it had rained last night (过去), it would be very cold today (现在).

比较if only与only if：

only if表示“只有”；if only则表示“如果……就好了”。If only也可用于陈述语气。
如：I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
        If only the alarm clock had rung. 当时闹钟响了，就好了。
        If only he comes early. 但愿他早点回来。 
It is(high) time that It is(high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
如：It is time that the children went to bed.
        It is high time that the children should go to bed. 
need“不必做”和“本不该做"”
didn't need to do表示：过去不必做某事，事实上也没做。
needn'thavedone表示：过去不必做某事，但事实上做了。
如：John went to the station with the car to meet Mary, so she didn't need to walk back home.
        约翰开车去车站接玛丽，所以她不必步行回家了。   
        John went to the station with the car to meet Mary, so she needn't have walked back home.
        约翰开车去车站接玛丽，所以她本不必步行回家了。(Mary步行回家，没有遇上John的车。)
典型例题：
There was plenty o ftime. She___.
A. mustn't have hurried
B. couldn't have hurried
C. must not hurry
D. needn't have hurried
答案：D。needn't havedone. 意为"本不必"，即已经做了某事，而时实际上不必要。 Mustn't have done用法不正确，对过去发生的事情进行否定性推断应为couldn't have done,“不可能已经”。must not do不可以（用于一般现在时）

特殊的虚拟语气词should 的用法：

1）It is demanded/necessary/a pity+that…结构中的主语从句的谓语动词要用should加动词原形，should可省略。
句型：
如：It is suggested that we(should) hold a meeting next week.
        It is necessary that he(should) come to our meeting tomorrow.
2）在宾语从句中的应用在表示命令、建议、要求等一类动词后面的从句中。order, suggest, propose, require, demand, request, insist, command, insist+(should)do
如：I suggest that we(should) hold a meeting next week. 
       He insisted that he(should) be sent there.
注意：如suggest, insist不表示“建议”或“坚持要某人做某事时”，即它们用于其本意“暗示、表明”、“坚持认为”时，宾语从句用陈述语气。
如：The guard at gate insisted that everybody obey the rules.
判断改错：（错）You pale face suggests that you(should) be ill. 
                    （对）Your pale face suggests that you are ill.
                    （错）I insisted that you(should) be wrong.
                    （对）I insisted that you were wrong.
3）在表语从句，同位语从句中的应用在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气，即（should）+动词原形。
如：My idea is that we(should) get more people to attend the conference.
        I make a proposal that we(should) hold a meeting next week.

虚拟条件句的倒装：

虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略，再把were, should或had移到从句句首，实行倒装。
如：Were they here now, they could help us.=If they were here now, they could help us.    
        Had you come earlier, you would have met him=If you had come earlier, you would have met him.    
        Should it rain, the crops would be saved.=Were it to rain, the crops would be saved.
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，即在从句中be用were代替。
如：If I were you, I would go to look for him.  如果我是你，就会去找他。
        If he were here, everything would be all right. 如果他在这儿，一切都会好的。
典型例题：_____to do the work, I should do it some other day. 
                   A. If were I
                   B. I were  
                   C. Were I  
                   D. Was I
答案：C. 在虚拟条件状语中如果有were, should, had这三个词，通常将if省略，主语提前，变成were, should, had+主语的形式。
但要注意，在虚拟条件状语从句中，省略连词的倒装形式的句首不能用动词的缩略形式。如我们可说Were I not to do.，而不能说Weren't I to do。

1、弄清虚拟语气 的含义和构成。
2、掌握各种虚拟语气的应用。

能力要求：掌握/应用
课时要求：2
考试频率：必考
分值比重：5