if用法总结

　求虚拟语气的全面总结

虚拟语气
语气 (mood)是一种动词形式，用以表示说话者的意图或态度。英语中的语气有三种：陈述语气、祈使语气和虚拟语气。
直陈语气(indicative mood),表示所说的话是事实。
祈使语气 (imperative mood),表示所说的话是请求或命令。
虚拟语气(subjunctive mood),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、建议或与事实相反的假设等。
一. 虚拟语气在条件句中的应用
学习虚拟语气在条件句中的用法之前我们必须清楚条件句的种类：条件句有真实条件句与非真实条件句(或称虚拟条件句)两种。真实条件句所表的假设是可能发生或实现的，句中的条件从句与结果主句都用陈述语气。
如：
If it doesnt rain tomorrow, I will go for a picnic. 假若明天不下雨，我就去野餐。
Oil floats if you pour it on water. 你如把油倒在水里，油就浮起来。
虚拟条件句所表的假设则是不可能或不大可能发生或实现的，句中的条件从句与结果主句皆须用虚拟语气。 条件从句主句与现在事实相反
If 主语 +动词过去式（be的过去式用were）should （would, might， could）+动词原形 与过去事实相反
If 主语 +had+过去分词should （ would, might， could）+ have ＋过去分词 与将来事实可能相反
If 主语 +动词过去式（be的过去式用were）； should＋动词原形；were to＋动词原形should （would, might， could）+动词原形
1. 与现在事实相反的虚拟条件句，条件从句的谓语用动词的过去式 (be的过去式用were), 主句的谓语用should （would, might， could）+动词原形。
如：
If it were not raining, we should go for a picnic.如果现在不下雨的话，我们就出去野餐了。
（事实是：天在下雨，我们不能出去野餐。表示愿望。）
If he came here, he might be able to help you. 如果他来这，他就能够帮助你了。
（事实是：他没来这，他不可能帮助你。表示对他的良好印象。）
2. 与过去事实相反的虚拟条件句，条件从句的谓语用had+过去分词，主句的谓语用should （ would, might， could）+ have ＋过去分词。
如：
She would have gone to the party if she had been invited.
要是当初她被邀请的话，她就会去参加这次聚会了。
（事实是：当时没有人邀请她，因此，她没有来参加聚会。表示后悔。）
If she hadnt called me, I would have overslept this morning.
今天早上，她要是不叫我的话，我就会睡过头了。
（事实是：她今天早上叫我了，我没有睡过头。表示感激。）
3. 与将来事实可能相反的虚拟条件句，条

件从句的谓语用动词的过去式(be的过去式用were)； should＋动词原形；were to＋动词原形，主句用should （would, might， could）+动词原形。
如：
If I were to be twenty years old next year, I would take the course of French.
明年我要是二十岁，我就会学法语。
（事实是：我现在已经老了，明年我学不了法语了。）
If it should fail, I would try again.要是失败了，我会再试一次。
（事实是：有可能失败，可我会再试。表示未知。）
虚拟过去式有时并不表示“不大可能实现的假设”，而是表示一种希望或不希望发生的动作。
如：
If we caught the early train, wed get there by lunch time.
假如我们赶上早班火车，到午饭时间我们就会到达那里了。(表希望)
If we missed the train, we should have to wait an hour at the station.
假如我们赶不上这班火车，我们就得在车站等一小时。（表不希望）
4. 混合型的条件句
当条件从句与主句所表的时间不一致时，虚拟语气的形式应作相应的调整。主句和从句的谓语动词并不相互呼应，这种条件句叫混合条件句。较多见的混合型条件句是从句用过去完成时（指过去行为），而主句用一般时（指目前状态）。
He would pass the test if he had taken my advice．如果他听了我的劝告，他现在会通过考试。
If I had spoken to him yesterday, I should know what to do now.
假如昨天我对他说了，现在我就知道该怎么办了。
You would be much better now if you had taken my advice.
假如你接受了我的意见，你现在就会好得多。
如条件从句用if I were...，主句则可用表任何时间的虚拟形式。
如：
If I were not busy, I would have come.
假如我不忙，我就会去了。(were表过去)
If I were you, I would go.
假如我是你，我会去的。(were表现在)
二. 连词if的省略
如果虚拟条件句的谓语部分有were，had和should时，可省略if，把were，had和should放到从句主语前面去，多见于书面语。
Had you not helped me, I should have failed.要是没有你的帮助，我就失败了。
Were you in my position, you would do the same. 假如你处在我的地位，你也会这样干的。
Should they attack us, well wipe them out completely.
假如他们进攻我们，我们就把他们彻底消灭干净。
三. 含蓄条件句
虚拟条件句中的条件从句有时不表出来，只暗含在上下文中，这种句子叫做含蓄条件句。含蓄条件句大体有三种情况。
1) 条件暗含在短语中。
如：
But for your help we couldnt have succeeded in the experiment.
如果没有你的帮助，我们的实验是不

会成功的。(暗含在分词短词but for your help)
What would I have done without you? 如没有你，我会怎么办呢？(条件暗含在介词短语without you 中)
It would be easier to do it this way. 这样做会比较容易。
(条件暗含在不定式短语 to do it this way中)
This same thing, happening in wartime, amount to disaster.
同样的事，如发生在战时，就会酿成大祸。(条件暗含在分词短语happening in wartime 中)
He must have the strength of a hippopotamus, or he never could have vanquished that great beast. 他一定是力大如河马，否则他绝不会击败那只庞大的野兽。(暗含条件是连词or)
Alone, he would have been terrified. 如是单独一人，他是会感到害怕的。(暗含条件是alone)
2) 条件暗含在上下文中。
如：
You might stay here forever. 你可以永远待在这儿。(可能暗含if you wanted to)
We would have succeeded. 我们本来是会成功的。(可能暗含if we had kept trying)
Your reputation would be ruined. 你的名誉会败坏的。(可能暗含 if you should accept it)
3) 在不少情况下，虚拟式已变成习惯说法，很难找出其暗含的条件。
如：
You wouldnt know. 你不会知道。
I would like to come. 我愿意来。
四. 不用if引导的条件从句
虚拟条件句中的条件从句除用if引外，还可用when, unless, lest, suppose, as if, for fear, in case, on condition 等词语来引导。
如：
The peasants prepared to feed the city when it should be freed.
农民已准备在这座城市解放后供给粮食。
Lest you should not have heard all, I shall begin at the beginning.
我怕你没有听全，所以我再从头开始讲一遍。
Unless I were well, I wouldnt be at school. 除非我好了，否则我不会上学。
Suppose you were given a chance to study in America, would you accept?
假如给你一个到美国学习的机会，你会接受吗？（suppose 或 supposing =what if）
Supposing it were so？（=Supposing it were so，what would happen？）
要是这样的话，会怎么样呢？
He can use the bicycle on condition that he should return it tomorrow.
如果明天能还回来，他就可以借用这辆自行车。
In case I forget , please remind me of my promise 如果我忘了，请提醒我的诺言。
Susan is walking slowly ,as if she were tired. 苏珊走得很慢，就像是累了似的。
与if一样，上述词语所引导的条件从句亦可用陈述语气，表可能实现或发生的事。
虚拟语气除主要用于条件句（也就是状语从句）外，还可用于主语从句、宾语从句、表语从句、定语从句等。
1. 虚拟语气在主语从句中的应用
“常用在It is (was)+形容词 / 过去分词+that

引导的主语从句”的句型中的主语从句要用虚拟语气。主语从句的谓语用should+动词原形(或should+have+过去分词)或只用动词原形(尤其是美国英语)。should在此是助动词，本身并无实义，这种主语从句中的should有时有感情色彩。
Its important that we（should）work out a plan. （带有“要求”的含义）
Its better that he go at once. （带有“建议”的意思）
☆ 用于本句型的形容词并不多，常见形容词有：necessary，important，best, right, impossible，preferable，desirable, imperative, advisable，essential，reserved，urgent， 等。
It is necessary that he（should）be sent there at once．
Its strange that he should say so.
I was glad that he should go.
It is important that we should speak politely.
It is a pity that she should fare so badly.
Its right that you should think that way.
☆ 用于本句型中的过去分词就是表示提议、要求、命令等动词的过去分词，如suggested，settled, required，requested，demanded，urged，decided, proposed，ordered，desired，advised等。
It is requested that Professor Liu（should）give us a lecture．
It is desired that we（should）get everything ready by tonight．
I’m ashamed you should have done such a thing.
It has been suggested that the meeting（should）be put off．有人建议推迟会议。
It is settled that you leave us, then?
注意：这种句型中的主语从句也可用陈述语气，如：It was important that he made an explicit statement on this score last week. 他上个星期对于这一方面做了明确的说明，这是很重要的。
2. 虚拟语气在宾语从句中的应用
1). 宾语从句在表示提议、要求、命令、意志等动词后，其谓语用should+动词原形或只用动词原形的虚拟语气，作为suggest，request，demand，urge，propose，prefer，advise，insist，require，order，command，maintain，ask，object, arrange, desire等动词的宾语。
如：
The doctor suggested that he not go there．医生建议他不要去那里。
He suggested that we should leave early. 他建议我们早点动身。
The judge ordered that the prisoner should be remanded. 法官命令被告还押。
2). wish的宾语的从句，表示愿望，常省去连词that。
☆ 从句的谓语动词可用过去式，表示现在的愿望（与现在事实相反），虽实现的可能性不大，但仍有实现的可能。
I wish it were true．我但愿这是真的。
☆ 从句的谓语动词还可用“could（would，might）+动词原形”用来表示将来的愿望
I wish you would stay a little longer.我希望你再待一会儿。
☆ 表示无能为力的过去愿望（与过去事实相反），可用“had +过去分词”或“coul

d（would，might）+have+过去分词”
I wish you had called yesterday．我希望你昨天来过电话。
We wish you had come to our New Year’s party.我们真希望你来参加了我们的新年联欢会。
3). would rather, would sooner等表示愿望，其宾语从句常用虚拟过去式。
☆ 表示与现在和将来含义事实相反的虚拟语气要用动词的过去式
☆ 用过去完成式(had + 过去分词)表示过去事实相反的含义
I would rather you came tomorrow.我宁愿你明天来。
Id sooner she left the heavy end of the work to some one else.我宁愿她把重活留给别人。
4). 有些动词，如think, expect, believe,其否定式的宾语从句亦可用should+动词原形。如：
I never thought he should refuse.我万没有想到他会拒绝。
She did not expect that you should come.她没有预料你会来。
3. 虚拟语气在表语从句中的应用
名词suggestion，proposal，order，advice，demand等作主语，其后的表语从句中的谓语动词一般使用虚拟语气，用should +动词原形或省略should。
My suggestion is that we (should) send a few soldiers to help them.
我的建议是我们应派几个战士去增援他们。
My advice is that you (should) treat her well. 我的忠告是你应该善待她。
He makes the demand that she (should) leave the place at once.
他提出一个要求，要求她立刻离开这个地方。
My suggestion is that we should tell him.我的建议是我们应该告诉他。
Our only request is that this should be settled as soon as possible.
我们唯一的请求就是尽快解决这个问题。
注意：虚拟语气也可以用于同位语从句。
如：
There was a suggestion that Brown should be dropped from the team.有一项建议是布朗应该离队。
4. 虚拟语气在定语从句中的应用
常用在It is time (that)…句型中，定语从句常用虚拟过去式
It is time the children went to bed. 孩子们早该上床睡觉了。（表示催促）
Its high time that he began to think how to deal with money.
他早该开始考虑如何与钱打交道。
It is time we left.我们该走了。
It is time we went to bed.我们该去睡觉了。
5. 虚拟式动词原形亦常用在独立句中，表愿望
Long live the Communist Party of China！中国共产党万岁！
God bless you! 上帝保佑你。
God damn it! 该死的！
The devil take you! 见鬼去吧！
So be it then. 就那样吧。
6. 虚拟时态与谓语动词时态的关系：从句中的虚拟时态往往不受全句谓语时态的影响。
1) 用于主语从句。试比较：
It is important that he should know about this.他必须知道此事。
It was important that he should know about thi

s.他必须知道此事。
2) 用于宾语从句。试比较：
I suggest that we should go tomorrow.我建议我们明天走。
I suggested that we should go the next day.我建议我们第二天走。
She said, “If I were a boy I would join the army.”她说，“我如是男孩，就参军。”
She said that if she were a boy, she would join the army.她说她如是男孩就参军。
但强调现在时刻的虚拟式在间接引语中需要遵守时态一致的原则。试比较：
“If I knew how it worked, I could tell you what to do,” he said.
“假如我知道它是如何运行的话，我就会告诉你该怎么办，”他说道。
He said that if he had known how it worked he could have told me what to do.
他说假如他知道它是如何运行的话，他就会告诉我该怎么办。
“If I knew the answer to all your questions Id be a genius,” he said.
“我如知道你所有问题的答案，我就是天才了。”他说道。
He said that if he knew the answer to all my questions, he’d be a genius.
他说他如知道我所有问题的答案，他就是天才了。
但如果全句谓语是虚拟语气，其后从句的时态则多受其影响，现在时态应随之而变为过去时态。
如：
I would think he was wrong.我看他是错了。(须用was,试比较：I think he is wrong)
It would seem that she was right. 她似乎是对的。(须用was,试比较：It seems that she is right)2010-7-26 20:42:30 【新】用QQ浏览器上网，阻手机入侵，保QQ安全，并送500Q币【QQ官方提供，永久免费使用】
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虚拟语态
一、虚拟语态的几种固定句式
1.I wish.....(一定用虚拟)
1）I wish i were you
2)I wish that she were here with me
2、as if...../as though 好象 (不一定用虚拟，要看说话的语境``)
1）He speaks as if he were an American.(如果他真的是美国人就不用虚拟了`)
2）He looks as if nothing had happened.
3、if I did/were....I would......
1)If I were you,I wouldnt do that
2)If it were to snow tomorrow,they would not go out
.(用were to 和were的区别是were to 是对将来的虚拟，
用were是对现在的虚拟`详见二、虚拟语态的几种形式```)
二、虚拟语态的几种形式
1、对现在的虚拟：（直接用动词的过去时....）
if I did /were.... i would.......
2、对将来的虚拟：if ..were to..I would....= if ..did...I would....
(此项与对现在的虚拟相同，但对现在的虚拟不用were to.
要区别对将来的虚拟和对现在的虚拟``一般句子里面都有时间标志``)
(If it were to rain tomorrow,we would not go out.
=If it rained tomorow,we would not go out.)
3、对过去的虚拟 If I had done....I w

ould have done....
(If I had know the answer, I would have told you.)
(至于If ..had been done ...would have done
前面的been只是因为是被动语态```所以要看句子的具体意思````)
另外。。固定句型的补充。。
要用虚拟语态的句子:
i would rather i could......(I would rather she could not come here)
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虚拟语气是一种动词形式，表示说话人的一种愿望，假设，怀疑，猜测， 建议等含义，虚拟语气所表示的含义不是客观存在的事实。

If I were you, Id take them away.

如果我是你的话，我就会带走他们。

If I had met Li Hua, I could had told him.

如果我碰见了李华，我就告诉了他了。

If I had time. I could come to help you.

如果我有时间，我会来帮助你的。

He suggested that our class should be divided into five groups.

他建议说我们的班应该分成五个小组。

He speaks to us as if he had been there.

他给我们讲的好象他去过那儿。

虚拟语气的用法

1) 虚拟语气用在简单句中，表示祝愿，命令。

May you be happy.

祝你幸福。

May you have a good time.

祝愿你玩的痛快。

May the friendship between us last long.

祝愿我们的友情天长地久。

Have a good journey!

祝愿你旅途愉快！

You go out！

你出去！

2) 虚拟语气用在宾语从句中。动词 wish, suggest,order,insist, propose,等词后面的宾语从句表示的是一种虚拟语气， 宾语从句中的动词动作表示的只是一种愿望，要求。

I wish she would be on my side.

我希望她能站在我一边。

I wish I could help him.

我希望我能帮助他。

He insisted that all of us should be there on time by any means.

他坚持要我们大家想尽办法按时去那儿。

动词 demand, suggest, order, insist, propose 后面的从句中，"should" 可以省略。