1、用来表示说的话不是事实，或者是不可能发生的情况，而是一种愿望、建议、假设的语气叫虚拟语气。(一)if主从句中的虚拟语气【完成例句】(1)如果我是你，我会接受邀请的。If I were you,I should accept the invitation.(2)如果我有空，我就去那儿。If I had time,I would go there.【结论1】条件与现在事实相反从句谓语用一般过去时(be多用were)主句谓语用 would/should/could/might动词原形【完成例句】(3)如果你早点来，你就不会错过那辆公共汽车了。If you had come earlier,you c
2、ouldnt/wouldnt havemissed the bus.(4)如果他昨天见到了你，他就会还你的书的。If he had seen you yesterday,he would have returnedyour book.【结论2】条件与过去事实相反从句谓语用had done主句谓语用would/should/could/mighthave done【完成例句】(5)万一明天下雨，运动会就推迟。(事实上明天下雨的可能性不大。)If it should rain/were to rain/rained tomorrow,thesports meet would be put off.
3、(6)万一杯子掉下来会打碎的。If you dropped/should drop/were to drop the glass,it would break.【结论3】条件与将来事实相反从句谓语用一般过去时(be多用were)或should 动词原形/were to do主句谓语用would/should/could/might动词原形【疑难1】含蓄虚拟句(即含有without/but for,otherwise/or等词的句子)【例句观察】Human beings would die without water.(Humanbeings would die if there were no
4、 water.)I couldnt have succeeded but for your help.(Icouldnt have succeeded if you hadnt helped me.)I had no money then.Otherwise I would have boughtthat book.(If I had had money then,I would have bought thatbook.)【疑难剖析1】含有without/but for，otherwise/or等词的句子谓语结构等同于if主从句中主句的谓语结构。与现在或将来事实相反would/should/
5、could/might动词原形与过去事实相反would/should/could/mighthave done【疑难2】含有had，should，were这三个词的虚拟条件状语从句Had they had time(If they had had time)，they would have certainly come to help us.Should it be fine(If it should be fine)，wewould go for an outing.Were I you(If I were you),I would go.【疑难剖析2】含有had，should，were这三
6、个词的虚拟条件状语从句，在正式或书面语言中可将if省略，把had，should，were 提前放到句首，变为部分倒装。【疑难3】if混合虚拟条件从句(即主从句分别与不同的事实相反)If the weather had been finer,the crops would begrowing still better.If you had followed the teachers advice,youwouldnt be in hospital.【疑难剖析3】if假设条件从句谓语动词发生的时间与主句所假设的谓语动词不一致，叫做错综条件虚拟语气。主句和从句的谓语动词要依照假设的时间而定。(二)用
7、虚拟语气，从句中谓语时态相应推后(即用相应的过去时态)的五种句型【完成例句】(7)他多么希望自己是只鸟。How he wishes that he were a bird.(8)我希望昨晚看了那部电影了。I wish I had seen the film last night.(9)我们希望有一天能住在月球上。We wish we would live on the moon one day.【结论1】在动词wish引导的宾语从句中，表示不太可能实现的愿望，从句必须使用虚拟语气。表示愿望与现在事实相反从句用一般过去时(did或were)表示愿望与过去事实相反从 句 用 过 去 完 成 时(h
8、ad done)表示愿望实现的可能性很小从句常用could/might/would do【完成例句】(10)我宁可你现在不在我身边。I would rather you were not here with me now.(11)我宁可你没做过那件事。I would rather you hadnt done that.【结论2】would rather/prefer that从句(从句用虚拟语气)表示愿望与现在事实相反从句用一般过去时表示愿望与过去事实相反从句用过去完成时【完成例句】(12)她英语说得好像她就是纽约本地人一样。She speaks English as though she
9、were a native ofNew York.【结论3】as if/though 从句中谓语用相应的过去时态(等同于wish从句用法)。【完成例句】(13)要是你没告诉我那个消息就好了。If only you hadnt told me the news.【结论4】if only(要是就好了)，句中谓语用相应的过去时态(等同于wish从句用法)。【完成例句】(14)我本来可以帮你忙的，即使我当时很忙。Even though Ihad been very busy then,I wouldhave helped you.(15)即使我现在能跑，我也不会那样做。Even if I might
10、run,I wouldnt do that.【结论5】even if/though 从句中的虚拟与现在事实相反用should动词原形与过去事实相反用had done(三)从句中所用的虚拟语气结构为should 动词原形，should可以省略。【例句观察】The doctor suggests I(should)exercise every day.医生建议我每天做运动。(宾语从句)It is suggested that I(should)exercise every day.我被建议每天做运动。(主语从句)The doctors suggestion is that I(should)exe
11、rcise every day.医生给我的建议是每天做运动。(表语从句)The doctors suggestion that I(should)exerciseevery day sounds reasonable.医生要我每天做运动的建议听起来挺合理的。(同位语从句)【结论1】名词性从句中，表示“建议，命令，要求”等意义时，名词性从句用(should)动词原形。一个坚持：insist两个命令：order,command(名词是order,recommendation)三个建议：advise,suggest，propose(名词是advice,suggestion,proposal)四个要求
12、：demand,require,request,desire(名词是demand,requirement,request,desire)注意：1.suggest 意为“表明，暗示”时，不用虚拟语气；如：His face suggested that he was very sad.2.insist意为“坚持认为，坚持说”时，不用虚拟语气；如：The man insisted my little brother was athief.【例句观察】我们应该掌握电脑知识，这是很重要的。It is important that we(should)have a goodknowledge of com
13、puter science.你居然没参加会议，真是可惜。It is a pity that you(should)be absent from themeeting.他竟然是名医生，我们很惊讶。We are surprised that he(should)be a doctor.【结论2】虚拟语气用在“Its形容词/名词that”这类句型中，表示说话人“强烈”的感情色彩，此时，从句用should 动词原形/should have done(表示动作在过去已经发生)，should 可译为“应该；居然，竟然”。should 可以省略。It is important/necessary/stran
14、ge/surprising/funny/natural that从句It is a pity/a shame/an honour/no wonderthat从句主语 be sorry/disappointed/surprised that从句【例句观察】以防错过第一班车，我们一大早就起床了。We got up early for fear that we should miss thefirst bus.We got up early lest that we should miss the firstbus.【结论3】在in case,for fear(that),lest等引导的状语从句中
15、，谓语动词用“should动词原形”。(四)几种特殊用法1.某些简单句的固定句型Heaven help him!God bless you!May you succeed!Long live the Peoples Republic of China!2.某些固定的词组和句型was/were supposed to have done 理应做was/were to have done 本计划做had thought/believed，but本以为had planned/intended，but本计划，本打算had wished/hoped，but本希望Its(about/high)time that从句，某人该做某事了