从句中 的虚拟语气
if条件句中的虚拟语气形式
1）if 非真实条件句所表示的假设则是不可能或不大可能发生或实现的，句中的主句与从句都用虚拟语气。
在if非真实虚拟条件句中，主句和从句谓语动词主要有下面几种形式：
假设类型 条件从句谓语动词形式 主句谓语动词形式
与现在事实相反 动词过去时（be 用 were） Should（would，could，might） + 动词原形
与过去事实相反 Had + 过去分词 Should（would，could, might）+ have + 过去分词
与将来事实可能相反 动词过去时（should+动词原形，were to + 动词原形） Should（would，could，might）+ 动词原形
If there were no gravity, we should not be able to walk.
假如没有引力，我们就不可能行走。
I wouldn’t have known what these were for if I hadn’t been told.
假如别人不告诉我，我就不知道这些东西是干什么的了。
2） 正式文体中，有时可把虚拟条件句中的连词if省去，而将were，had, should等助动词（不包括行为动词）提到主语前面。如果句中没有were，had或should时，既不能省略if，也不能倒装。例如：
Were I to meet him tomorrow (= If I were to met him tomorrow), I should ask him about it.
要是我明天见到他，我就会问他这件事的。
Had I had the money last year (= If I had had the money last year), I would have bought the house.
如果我去年有了这笔钱，我就买那所房子了。
Should there be any trouble with the boiler, the automatic controlling unit would cut off the fuel oil supply.
假如锅炉出问题的话，自控装置会自动切断燃油的供给。
3） 通常情况下，在非真实条件句中主句和从句的谓语动词所指时间是一致的，但有时也可能指不同的时间，这时要根据上下文的意思采用不同的谓语动词形式。例如：
If I were you, I would have taken his advice.
我要是你，我就采纳了他的建议。（从句指现在，主句指过去）
If the weather had been more favorable, the crop would be growing still better.
如果气候更适宜一些，庄稼会长得更好。（从句指过去，主句指现在）
含蓄虚拟条件句
1）有时假设的情况并不以条件从句形式表示出来，而是通过一个介词短语或其他方式表示。常用的词或短语有：without, but for, but that, otherwise, or, but 等。例如：
Without your help (=If we had not had your help), we could not have succeeded.
要是没有你的帮助，我们就不会成功的。
But for electricity (= If there were no electricity), there would be no modern industry.
要是没有电，就不会有现代工业。
He was having a meeting; otherwise he would have come over to help us.
他当时正
与他的学生进行讨论，否则的话他就来帮我们了。
He felt very tired yesterday, or he would have attended the party.
他昨天很累，不然他就参加那个聚会了。
2）在某些暗含虚拟条件的简单句中，虚拟语气可通过上下文表现出来。谓语动词用should/ would be 形式和should/ would have been 虚拟形式。例如：
Any men in his position would have done like that.
任何人处在他的位置都会那么做的。
You should (ought to) have come earlier.
你本应来得早点。
其他句型中的虚拟语气
1）在would rather, would sooner, would just as soon, might as well和would prefer等后面所跟的从句中，也可以用虚拟语气，表示愿望，意为“宁愿、但愿”。其形式为：
①“would rather (would sooner…) + 主语 + 谓语动词过去式” 表示现在或将来的情况。
②“would rather (would sooner) + 主语 + 动词过去完成式”表示过去的情况。例如：
I’d rather he didn’t go now.
要是他现在不走就好了
I’d just as soon you had been here yesterday.
要是你昨天在这里就好了。
2）在句型“It is (high/ about) time…”后面也可以跟虚拟语气，从句中常用过去式。有时也用“（should）+ 动词原形”，意为“该是……的时候了”。例如：
It is time that the boy (should) go to school.
这个小孩该上学了。
It is high time (that) the weather improved.
天气真该好起来了。
3）在“if only”引起的感叹句中也要求用虚拟语气，表示愿望。
形式为：①用过去时或“would/ could + 动词原形”表示与现在或未来事实相反的愿望。
②过去完成时表示与过去事实相反的愿望。例如：
If only you would listen to our advice.
要是你听我们的建议就好了。
If only I had not been busy last week!
要是上周我不忙该多好啊！
If only she could marry me.
但愿她能嫁给我。
注：if only也可以用于虚拟条件句中。例如：
If only I had more money, I could buy a car.
要是我有更多的钱，我就可以买辆车了。
4）连接词“in case, lest, for fear that”可以用来引导虚拟语气。其形式通常为：“…lest (in case, for fear that) + 主语 + should + 动词原形”。Lest, for fear that 句中的 should 可以省去， in case 句中的 should 通常不省去，但是 in case 句中可以不用虚拟语气，而用陈述语气。Lest, for fear that后面也可以接其他形式。例如：
He took his coat with him in case it should rain.
他带着雨衣以防下雨。
I will not make a noise for fear that I (should/ might) disturb you.
我不会做声的，以免打扰你。
Care must be taken in using this met
hod lest overflow (should) occur.
在使用这以方法的时候要谨慎小心，以免发生溢流现象。
虚拟语气的考点可以归纳如下：
1. (should)+动词原形的情形(已考)
2. if或but for等引导的条件句(已考)
3. wish, if only, it is time…的用法
(should)+动词原形的情形
1.在动词suggest, order, demand, propose, command, request, desire, insist, require, decide, promise, resolve, argue, maintain, determine, recommend, advise, advocate, persuade等表示“命令”、“建议”、“要求”动词后的宾语从句中。
She insisted that the seats (should) be booked in advance. 她坚持要预定座位。
He advised that the doctor (should) be sent for. 他劝我们派人请医生。
注：如果上述动词作其他意思解释，或者说话者认为所讲的事是事实，要用陈述语气。
When asked why he declined our invitation, he suggested that he was not on good terms with the director.
真题重现
【CET-4:2006.6】The professor required that __________________(我们交研究报告)。
参考答案：we hand in our research report(s)
2.在advice, demand, order, necessity, resolution, decision, proposal, requirement, suggestion, idea, recommendation, request, plan,等名词后的主语从句或表语从句中------上面动词对应的名词
He issued the order that the troops (should) withdraw at once. 他命令部队马上撤退。
3.在形容词important, necessary, imperative, natural, urgent, essential, appropriate, desirable, vital, advisable, preferable, incredible以及短语no wonder, a pity等可以构成“It is +形容词(名词)+that”句型中。
It is necessary that some immediate effort (should) be made. 必须立即采取行动。
真题重现
【CET-6:2007.6】It is absolutely unfair that these children ______(被剥夺了受教育的权利).
参考答案：These children (should) be deprived of the right to receive education.
if或but for等引导的条件句★★★
if引导虚拟条件句的用法
条件从句 结果主句
与现在事实相反 动词过去式(be动词用were) would+动词原形
与过去事实相反 had+过去分词(had done) would have done
与将来事实相反 一般过去时/were+不定式/should+动词原形 would(should)+动词原形
He wouldn’t feel so cold if he were indoors.他要是在室内就不会觉得冷了。(与现在事实相反)
I am sorry I am very busy just now. If I had time, I would certainly go to the movies with you.
我很抱歉，现在很忙。如果有时间，我肯定陪你去看电影了。(与现在事实相反)
The conference wouldn’t have been so successful if we hadn’t made adequate preparations.
如果我们不做充分的准备
，会议是不会开得这么成功的。(与过去事实相反)
If it snowed/were to snow/should snow tomorrow, I should (would) stay at home.
but for=if it were not for…/if it had not been for…l
But for your help they would not have fulfilled the task in time.
真题重现
【CET-4:2006.12】The victim _______________________(本来会有机会活下来)if he had been taken to hospital in time
参考答案：would have survived
【CET-6:2007.12】But for mobile phone, ____________________.
我们的通讯就不可能如此迅速和方便)
参考答案：our communication would not have been so efficient and convenient.
【CET-6:2007.1If you had ___________________(听从了我的忠告， 你就不会陷入麻烦).
参考答案：followed my advice/suggestion, you would not have been in trouble.
It is (high, about) time …句型要求用虚拟语气
谓语动词用过去式，指现在或将来的情况，表示“早该干某事而已经有些晚了”。
★★It’s time_____________________(采取措施) about the traffic problem downtown.
something was done/some measures were taken
动词wish后的宾语从句用虚拟语气
与现在事实相反 were或动词的一般过去式
与过去事实相反 had done或would/could have done
将来没有把握或不太可能实现的愿望 would/should(could, might)+动词原形
I wish she were here. 她在这里就好了。
I wish you would go with us tomorrow. 但愿你明天跟我们一块去。
I wish she had taken my advice. 那时她要是听我的话就好了。
if only后用虚拟语气(要是…就太好了)
现在没有实现的愿望 一般过去式
过去没有实现的愿望 过去完成式
If only she had known where to find you. 他要是知道到哪里去找你就好了。
If only I could speak several foreign languages!我要是能讲几种外语就好了!