虚拟语气语法总结 英语中虚拟语气有什么用法？举一下例子，谢谢！

英语中虚拟语气有什么用法？举一下例子，谢谢！  

英语中虚拟语气有什么用法？举一下例子，谢谢！

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.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 主句
一般现在时shall/will + 动词原形
If he es, 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.
(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。
2.非真实条件句
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 ： 条件从句 主句
一般过去时 should( would) +动词原形
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 主句
过去完成时 should(would) have+ 过去分词
If she had worked harder, she would have sueeded.
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.
If he had e yesterday, I should / would have told him about it.
含义：He did not e yesterday, so I did not tell him about it.
If he had not been ill and missed many classes, he would have made greater progress.
含义： He was ill and missed many lessons, so he did not make greater progress.
c. 表示对将来的假想
句型： 条件从句 主句
一般过去时 should+ 动词原形
were+ 不定式 would + 动词原形
should+ 动词原形
If you sueeded, everything would be all right.
If you should sueed, everything would be all right.
If you were to sueed, everything would be all right.
3.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。
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).
4.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。
Were they here now, they could help us.
=If they were here now, they could help us.
Had you e earlier, you would have met him
=If you had e 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。
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 IB. 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.
5特殊的虚拟语气词：should
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：
(1)suggested
It is (2)important that…+ (should) do
(3) a pity
(1)suggested, ordered, proposed, required, demanded, requested, insisted； + (should) do
(2)important, necessary, natural, strange
a pity, a shame, no wonder
例：It is suggested that we (should) hold a meeting next week.
It is necessary that he (should) e 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, mand, insist + (should) do
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。
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。
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.
6.wish的用法
1）用于wish后面的从句，表示与事实相反的情况，或表示将来不太可能实现的愿望。其宾语从句的动词形式为：
真实状况 wish后
从句动作先于主句动词动作 过去时 过去完成时
（be的过去式为 were）
从句动作与主句动作同时发生 现在时 过去时
（had + 过去分词）
将来不大可能实现的愿望 将来时 would/could +
动词原形
I wish I were as tall as you. 我希望和你一样高。
He wished he hadn't said that. 他希望他没讲那样的话。
I wish it would rain tomorrow. 我希望明天下雨就好了。
2）Wish to do表达法。
Wish sb / sth to do
I wish to see the manager. = I want to see the manager.
I wish the manager to be informed at once. (= I want the manager to be informed at once.)
7.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。
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 es early. 但愿他早点回来。
8.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。
It is time that the children went to bed.
It is high time that the children should go to bed.
9 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't have done表示： 过去不必做某事, 但事实上做了。
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 of time. 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 have done. 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）。
语气是一种动词形式，用以表示说话者的意图或态度。虚拟语气表示说话者的主观愿望、假想和建议等，所说的话有的与现在事实相反，或与过去事实相反，或与将来事实相反或与将来事实可能相反。所以虚拟语气总是与假设条件句用在一起。除了if条件句外，还有几种常用的条件句，短语也可表示条件。此外，上下文也能创造虚拟的语言环境。但有时条件从句与结果主句可能发生时间不一致，有时虚拟语气会出现倒装情况。除了与条件句在一起使用的主句用虚拟语气外，有些宾语从句或表语从句也有用虚拟语气的情况。

请问一下英语中虚拟语气怎么用，谢谢了！

虚拟语气是在和现在事相反的状态下；或者是假设{ if i were you }，或建议的状态下用

英语中有什么词可以用虚拟语气？

现代英语中，通用的动词虚拟式只有两个，即be型虚拟式和were型虚拟式。所谓be型虚拟式，是指不管主语是什么人，动词一律用原形，如果动词是被动态形式，则助动词一律用be。所谓were型虚拟式，是指不管主语是什么人称，动词一律用were，动词是进行时或被动态时，助动词一律用were。
be型虚拟式
1.用于表示命令、决定。建议等词语后的that分句。例如：Mary insisted that John e. /He ordered that the books be sent at once.
2.用于if,though,whatever,lest等引导的分句中，表示推测、让步、忧虑等。例如：Though everyone desert you,I will not. /If John be found guilty,he shall have the right of appeal.
3.用于某些表示祝愿、诅咒、禁止等以及公式化的语句中。
例如：
God bless you! /Heaven forbid!
were型虚拟式
1.用于wish后的that分句中，表示与现在的事实相反的主观设想。例如：
I wish I were there.
I wish it were spring all the year round.
2.用于if,as if,as though等引导的分句和suppose或imagine等后面的分句中，表示对现在时间或将来时间的主观设想。例如：
If I were you,I should wait till next week.
He spoke to me as if I were deaf.
If it were to rain,we should get wet.

英语中虚拟语气should不能省的情况

Itis(high)timethat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。
Itistimethatthechildrenwenttobed.
Itishightimethatthechildrenshouldgotobed.

谁还记得英语中虚拟语气的规律啊

英语动词中一般有三种语气：用来陈述事实的陈述语气；用来表示命令、请求或劝告的祈使语气；还有用来表示与事实相反的假设、愿望、建议的虚拟语气。历年来，体现英语交际功能并能考查学生对对话语境，说话者语气理解能力的虚拟语气相关试题在高考中不断出现。请看下面一些例题： 1. I didn't see your sister at the meeting. If she had e, she would have met my brother.(NMET'94)2. When a pencil is partly in a glass of water, it looks as if it were broken. (NMET'95) 3. You didn't let me drive. If we had driven in turn, you wouldn't have got so tired. (NMET'96)4. Should it rain tomorrow, we should have to put off the visit to the Yangpu Bridge. (上海94 )由此可见，掌握好虚拟语气很重要。在学习中，学生一向把它列为难度大、形式多样、不易掌握的语法专案之一。同时，虚拟语气考题也是学生易失分的一个方面。其实，虚拟语气主要是考查学生对虚拟语气谓语动词形式的掌握。而虚拟语气动词形式多样，有should+动词原形；有动词用过去式，过去完成时；有would (could，should，might )+动词原形等等。困难就在学生不能清楚记忆什么情况下用哪种动词形式。于是，针对此问题，笔者就虚拟语气动词形式进行研究、分析，摸索出一定的规律，把虚拟语气根据动词形式归类成如下三种。一、非真实条件句中的虚拟语气形式(即三个公式)。1.与现在事实相反的。条件从句主句动词用过去式(be的过去式一般用were)主句would(could,should,might)+动词原形(should只用于主语为第一人称)例：If I had time now, I would go to the cinema with you. The boy is not hungry. If he were hungry, he would eat the cake.2.与过去事实相反的。条件从句had+过去分词主句would(could,should,might)+have+过去分词(should只用于主语为第一人称)例：If he had been warned, he would not have taken that food. Luckily he was sent to the hospital immediately.We didn't know her address. If we had known it, we would have sent a note to her.3.与将来事实可能相反的。条件从句主句动词三种形式可用：动词过去式should+动词原形were to+动词原形would(could,should,might)+动词原形例：If it should rain (rained或were to rain) tomorrow, we would have to put off the visit to the Great Wall.［注意］1.虽然有些句中没有明显的if条件从句，而是通过一些介词短语如but for, without或分词短语或副词otherwise等来表示一个含蓄的条件，相当与一个if条件句，这种情况下要注意主句动词虚拟语气形式。例：But for the efforts of the captain , the ship would have sunk.(If it had not been for the efforts of the captain,...)Given more attention, the trees would have grown better. (If the trees had been given more attention,...)I was very busy then. Otherwise I would have helped you with your work.(I was very busy then. If I had not been busy then,...)2.在虚拟语气中，如果if条件从句有were或助动词should/had,可以把if省略,把were /should /had移至句首,用倒装句。例：If it had not been for the efforts of the captain, the ship would have sunk with all the passengers.可省略if ,把had移至句首，改为：Had it not been for the efforts of the captain, the ship would have sunk with all the passengers.二、(should )+动词原形的虚拟语气形式。下列几种情况用(should) +动词原形的虚拟语气形式。1.在It is natural(important, necessary等)that...句型。例：It is natural that you (should) say apology to him.It is necessary that he (should) be sent to hospital at once.2.用于表示命令、建议、要求一类动词后的宾语从句，如suggest，order，insist，demand，request，mand等。例：The young man insisted that he(should) be sent to do the work.I suggested that we (should) set off earlier.［注意］当insist表示对已发生过的事物的看法，或当suggest为"说明了"，"暗示"的含义时，从句用陈述语气而不用虚拟语气。The Arab insisted that he hadn't seen the camel.His smile suggested that he was happy.当表示命令、建议、要求等名词作主语时，其表语从句也用(should)+动词原形的虚拟语气形式。这类名词有suggestion，request，order，advice，idea等。例：The officer's order was that his soldiers should repair the defence works at once.His advice is that your father should do more exercises in the morning.上述名词的同位语从句中也应用(should)+动词原形。例：I did not receive the order that you(should) leave here at once.His suggestion that you (should) keep silent is reasonable.三、谓语动词用过去时(即过去式，过去完成时)的虚拟语气形式。在wish, would rather, as if, if only等后面的从句，如表示与现在事实相反，其谓语动词用过去式；如表示与过去事实相反，其谓语动词用过去完成时。其中wish后的宾语从句如表示与将来事实相反，谓语动词则用would或could +动词原形；would rather后的宾语从句如表示与将来事实相反，动词仍用过去式；as if引导的从句如表示与事实相符则不用虚拟语气形式。在虚拟语气中be的过去式一般用were。例：-Did you go to the party yesterday?-Yes, but I wish I hadn't. (gone to the party yesterday)I would rather you went next Sunday.I would rather you hadn't done that. If only you had followed my advice.She loves the child as if he were her own.经过以上归类，学生就能巧记变化多样的虚拟语气形式，从而更好地掌握运用虚拟语气。

怎么用英语解释虚拟语气啊，谢谢各位了！

In grammar, the subjunctive mood (sometimes referred to as the conjunctive mood) is a verb mood that exists in many languages. It typically expresses wishes, mands (in subordinate clauses), emotion, possibility, judgement, necessity, and statements that are contrary to fact at present. The details of subjunctive use vary from language to language.

英语中被动语态和虚拟语气怎么用

虚拟语气
在虚拟语气中，除了记住一套与时态相对应的规范用法之外，以下几点也是不容忽视的：
l、名词性从句中要用过去时或should+动词原型构成虚拟语气。如：It is time we went home。
2、would rather,hadr ather后的从句动词用相当于陈述语气的过去时来表示现在或将来发生的动作。如：I would rather you went with her。我宁愿你跟她走。只有当would rather后面动作的主体与前面主语一致时才可以用不带to的动词不定式，如：I’d rather take the important letter with me。在这个句子中，rather后面的主语为I，和前面的主语一致，所以用的不是过去式，而是不带to的动词不定式。
3、在it is important/suggested/necessary/proposed等结构后的主语从句中要用虚拟语气表示应该做什么事情，即用动词原形或should+动词原型，如：It is important that you(should)be here on time。再如：
It is of the utmost importance that you_______here on time。
A.be B.shall beC.are to be D.must be
这个知识点是上文中的第三点，显然答案是A，其中的should被省略了。类似的可以引起主语从句为虚拟语气的形容词或过去分词还有appropriate,advisable,better,imperative,insistent,natural,preferable,strange,urgent,vital,desirable,demanded,remended, required等。
4、片语but for相当于wereitnotfor或had it not been for,表示一种含否定意义的条件，后面一般加名词或名词短语，如：He might have been killed but for the arrival of the police。要不是警察来了他本可能被杀死。
5、在某些表示祝愿的句子里需要用虚拟语气，如：May you be happy all your life
被动语态
被动语态是大家十分熟悉的一种语法现象，由be+ved分词构成。有时候用介词短语by表明执行者。关于被动语态应注意的几个方面：
1、不及物动词seat的用法。例：When I______,the play started。
A.wass eated B.seatedC.was seating D.was being seated
在这道题里，不及物动词seat的用法十分特殊，当表示坐下、就座、坐着的意思时，只能用“be+ed”结构，这里它看似被动语态，实际上并不表示被动，而是一个形容词化了的动词。所以正确答案是A。
2、没有被动语态的及物动词。例：the book I bought yesterday________me enty dollars。
A.is costed 　B.costing　C.costs D.was costed
这里的正确答案为C，因为有些及物动词并没有被动语态。所以当这些词表示动作或状态时不能用被动语态而需要使用主动语态。这些词还有：beg,contain,bee,cost,equal,fail,fit,have,hold,lack,possess,resemble等。此外，还有一些及物动词短语如result ,from,belong to和consistof等，也没有被动语态。
语法问题就要找个专业点的老师详细解答，在网上问的话永远也记不牢靠。你还是找个英语老师进行系统讲解吧！听说奥威斯发展大厦29层不错，你可以去那里试听一下我的朋友就在那里学习。

英语中 主将从现和虚拟语气有什么联络? 有什么区别? 具体点解释~ 谢谢~

与虚拟语气无关。主将从现只用于时间状语从句和条件句。
1. 时间状语从句：明天他来时，我会告诉他的。I will tell him when he es tomorrow.
2. 条件句：如果明天下雨，我们就呆在家里。 If it rains tomorrow, we will stay at home.
虚拟语气属于条件句。而真实的条件句都必须用陈述语气。（比如上一句）
虚拟语气基本上分三种时间段：
1 对过去发生完的事情，埋怨，或猜测。如：如果你不去那里的话， 就不会发生这事情了。
If you had not gone there, it would not have happened.
2. 对现在的推测，如：如果我是你的话，我就去那里。If I were you, I would go there.
3. 对未来推测，如：如果明天地球没有水的话，我们怎么办？What should we do if there should no water on the earth tomorrow?

高一英语虚拟语气

虚拟语气是以动词的特殊形式来说明句中所叙述的内容不是事实，或是不可能发生的事情，而是一种愿望、建议或是与事实相反的一种假设。虚拟语气通常出现在各种主从复合句中。
一、在宾语从句中
1．当主句的谓语动词为“suggest，propose，advise，insist，order，demand，require，request， desire’’等表示“建议”、“命令”、“请求”和“要求”的动词时，其后的宾语从句中要用虚拟语气“should+动词原形”(在美国英语中 should省略)。例如：
I suggest that we(should)hold a meeting tonight．我建议我们今晚开个会。
We advise that steps(should)be taken at once．我们建议要立刻采取措施。
They insisted that he(should)begin the work at once．他们坚持让他立刻开始工作。
He ordered that aU(should)take part in the work．他下令所有的人都要参加这项工作。
另外，当主句动词为“ask，move，urse”等意为 “要求”、 “提议”和“极力主张”时，其宾语从句也常用虚拟语气。例如：
He asked that he be given an opportunity to try．他要求给他一个尝试的机会。
I move that the money be used for books． 我提议把这笔钱用于买书。
They urged that we take action on this matter immediately．他们极力主张我们对这件事立即采取行动。
2．当主句动词为wish，表示“但愿……”，“要是……该多好叼”之意时，其后的宾语从句有以下三种虚拟语气形式。
①动词用过去式来说明与现在的事实相反(BE动词常用were，但有时也可用was)。例如：
I wish 1 were／Was as strong as you．我要是像你一样强壮就好了。
I wish l remembered his address．我要是记住他的地址就好了。
有时；为了强调现在状态下能发生某种情况或进行某项动作，从句中的动词也可用过去进行式。例如：
I wish it wasn’t raining．要是天不下雨就好
了。
②动词用过去完成式说明与过去的事实相反。例如：
We wish we had paid more attention to our pronunciation．我们以前要是能更注意我们的发音就好了。
He wished he had stayed at home。他但愿他呆在了家里。
③情态动词“would，could，might”等后接动词原形，表示对将来的希望(通常不用should)。例如：
I wish he would try again．我希望他再试一下。
We wish he could e．我们希望他能来。
3．在prefer之后的宾语从句中用“should+动词原形”(should可省略)。例如：
We prefer that the plan(should)be fully discussed before being put into execution．我们希望在计划实施之前进行认真的讨论。
4．在would rather之后的宾语从句中，其动词用虚拟语气，表示句子的主语(某人)宁愿让另一人做某事。
①用动词过去式表示现在或将来要做的事。例如：
I’d rather you went home now．我宁愿让你现在就回家。
Don’t e tomorrow．I’d rather you came nexeekend．明天别来，我宁愿你下个周末来。
一Shall l open a window?我开窗行吗？ 一I’d rather you didn’t．你最好别开。
②用动词的过去完成式表示过去的动作。
例如：
I’d rather you hadn’t done that．我真希望(宁愿)你没做过那件事。
二、在主语从句中
1．在句型“h is／was+过去分词+that从句”中，当过去分词为“suggested，ordered，desired，insisted， required，demanded，requested，decided，proposed，urged’’等时，从句中要用“should+动词原形”(should可省略)。例如：
h is desired that everyone(should)get erything ready bY toniShL要求每一个人在今晚之前要将一切准备好。
It is requested that Miss Zhang(should) give a performance at the party．请求张小姐在晚会上表演一个节目。
2．在句型“h is／Was+形容词+that从句”中，当形容词为“important,necessary，strange，natural’’等时，从句中要用“should+动词原形”(should可省略)。例如：
It is important and necessary that we should master a foreign language．掌握一门外语对我们来说是重要的和必要的。
It is strange that he (should) refuse your help．他竟然拒绝你们的帮助，真奇怪。
3．在句型“h is／was+名词+that从句” 中，当名词为“a pity，a shame，no wonder’等时，从句中要用“should+动词原形”(should可省略)。例如：
It is a great pity that he should be so selfish。真遗憾，他竟然那么自私。
三、在同位语从句或表语从句中
在名词“suggestion,proposal,idea,plan，order,advice’’等后面的同位语从句或表语从句中，用“should+动词原形”(should可省略)。例如：
I made a proposal that we(should)hold a meeting next week．我提出了我们下个星期开会的建议。(同位语从句)
His suggestion that the meeting(shoald)be held in this room has been aepted．他的关于在这个房间召开会议的建议被采纳了。(同位语从句)
My idea is that we(should)get more people to attend the conference．我的想法是我们多找些人来参加会议。(表语从句)
四、在定语从句中
在句型“h is(high)time+(that)从句”中，谓语须用虚拟语气。用过去式表示现在或将来的意念，意为“现在是该做某事的时候了”。
例如：
It iS(high)time(that)we went home．我们该回家了。
五、在状语从句中
1．在假设条件句的if条件从句中
假设条件句一般是由“if引导的条件从句+主句”构成。if从句中的谓语动词要用虚拟语气的形式。if从句的假设可以是与现在事实相反的条件、与过去事实相反的条件或者与将来不太可能成为事实的条件。下面分述表示这三种条件的if从句的结构：
①与现在的事实相反，其句子结构为“If+主语+were／谓语动词的过去式”。例如：
If I were you，I shouldn’t do that．如果我是你，就不会做那件事了。
We would go with you if we had time．如果我们有时间的话，就和你一道去了。
We could ask him if he were here．如果他在这儿，我们就可以问他了。
②与过去的事实相反，其句子结构为“If十主语+谓语动词的过去完成式”。例如：
If he had seen you yesterday，he would have asked you about it如果昨天他见到你，他就会问你那件事了。
If you had e earlier，you would have met him．如果你早点儿来，就会遇到他了。
1 would have called you if I had known your telephone number．如果我知道你的电话号码，就打电话给你了。
③表示将来不太可能实现的条件，其句子结构为“If+主语+动词过去式／were to+动词原形／should+动词原形”。例如：
If he came tomorrow,he would find me in the schoo1．如果他明天来的话，会在学校找到我。
If it should rain，the crops would be saved．如果下雨，庄稼就有救了。
If it were to snow tomorrow，they would not go out．如果明天下雪，他们就不出去了。
注：在if从句中，如果含有“were，should，had’’时，可省去if而将“were，should，had’’置于句首，构成倒装句。例如：
Were l in your position，1 would go．如果我处在你的位子上，我就走了。
Had you arrived five minutes earlier，you could have seen them off．如果你早到五分钟，
你就可以给他们送行了。
Should he e，tell him to ring me up．如果他来的话，叫他打电话给我。
2．在目的状语从句中
①在由lest
和in case等引导的目的状语从句中，用“should+动词原形” (should可省略)。例如：
He ran away lest he(should)be seen．他跑走了，以免被人看到。
She explained again and again in case he (should)misunderstand her．她解释了一遍又一遍，以免他误解她。
in case等引导的目的状语从句中的谓语有时也可用陈述语气。此时，从句表示的就是真实情况，而不是虚拟情况。例如：
Take warm clothes in case the weather is cold．带上厚衣服，以防天气变冷。
②在由“so that…”和“in order that…”
引导的目的从句中，要用“can／could／may／might／would+动词原形”，以表示目的并非事实。例如：
She stayed at home for a few days so that
she might／could take care of her sick mother． 她在家呆了几天，以便照顾她生病的母亲。
③在由“for fear that…”引导的从句中，用“should+动词原形”(有时也可用may／might／would)。例如：
He worked hard for fear that he should fail．他努力学习，害怕考试不及格。
3．在方式状语从句中
由as if和as though等引导的方式状语从句中，如果从句所表达的情况是虚拟的，则①常用动词的过去式来表示与现在或当时的情况相
反；如果是BE动词，则用were；②常用过去完成式来表示与过去的情况相反。例如：
She loves the child as if he were her own．她爱这孩子就好像是她亲生的。
(实际上不是她亲生的孩子)
Holding his head high，he walked past the pole and the soldiers as if they didn’t exist．他昂着头从旗杆和卫兵身旁走过，就像他们不存在似的。(实际上他们是存在的)
He speaks English as well as ifhe hadstudied in England．他英语说得这么好，好像他去英国学过英语似的。(实际上他没有在英国学过英语)
4．在原因状语从句中
在“I’m sorry that．—／We were surprised that一．／They were disappointed that．．．”等引导的表示原因的状语从句中，用“should十动词原形”。例如：
I’m sorry that he should be in such poor health．他的身体这么差让我很难过。
We were surprised that she should be so stubbom．她这么固执让我们感到奇怪。
上述句子有时也可以用陈述语气，但这仅表示所叙述的是事实，而不表示讲话人的情绪。
虽然是搜来的，我也从中学到很多呢，呵呵，希望能对你有帮助！