英语语法---虚拟语气

非真实条件句中谓语动词的形式

与现在事实相反 If I (we,you,he,they)+ 动词过去式(be的过去式用were) I(we) should.You would. He would .They would+动词原形 与过去事实相反 If I (we,you,he,they)+had+过去分词 I(we) should.You would.He would .They would +have+动词原形 与将来事实可能相反 If I (we,you,he,they)+ 动词过去式(be的过去式用were)/were to/should I(we) should.You would. He would .They would +动词原形 但要注意：美国英语的结果主句，不管什么人称，皆常用would。

与现在事实相反的非真实条件句

虚拟语气用在与现在事实相反条件句中时，条件从句的谓语用动词的过去式 （be的过去式用were），结果主句的谓语用should(第一人称)或would(第二、三人称)＋动词原形。如：

I am sorry I am very busy now. If I had time, I would certainly come to see you. 很抱歉，我很忙。如果有时间，我一定去看你了。

If it weren’t for their support, we would be in a difficult situation. 要不是有他们的支持，我们的处境会很困难。

if places were alike, there would be little need for geographers. 如果各个地方都一样，就不需要地理学家了。 If I were you, I would apply for the job. 如果我是你，我会申请那份工作的。

What would you do if you knew who broke the glass. 要是你知道谁打破了玻璃，你会怎么办？

Even if I had the money, I wouldn’t buy it. 即使我有钱也不会买它。

与过去事实相反的非真实条件句

虚拟语气用在与过去事实相反的条件句中时，条件从句的谓语用had＋ 过去分词，结果主句的谓语用should(第一人称) 或would（第二、三人称） ＋ have＋ 过去分词。如：

If I had taken your advice, I wouldn’t have made such a mistake. 如果当时听了你的话，我就不会犯这样的错误了。

If it had not been for your help, I wouldn’t have finished the work so easily. 要不是你的帮助，我的工作不会这么容易完成。

If we had known the basic principles, we should have controlled the process even better. 如果我们知道这些基本原理，我们早就能更好地控制这个工序了。

If facts had been collected one week earlier, we should have had more time to study them.

假使早一个星期收集事实，我们就有更多的时间研究它们了。

The conference wouldn’t have been so successful if we hadn’t made adequate preparation. 如果我们不做充分的准备，会议是不会开得这么成功的。

与将来事实相反的非真实条件句

（1）虚拟语气用在与将来事实相反的条件句中时，条件从句的谓语用动词的过去式（be的过去式用were），were to或should，结果主句用should(第一人称)或 would（第二、三人称）＋ 动词原形。如：

If it rained( were to rain/ should rain) tomorrow, I should stay at home. 如果明天下雨，我会呆在家里。

If the teacher knew it, he would be angry. 万一老师知道了这事，他会生气的。

I wouldn’t lose courage even if I should fail again. 即使再次失败我也不会气馁。

If I made a mistake, I should try to remedy it. 假如我犯了错误，我就会设法补救。

If something should go wrong, the control rods would drop. 万一发生什么事故，控制杆就会下落。

(2) 在与将来事实相反的条件句中，其条件从句的谓语也可用were to ＋ 动词原形。这种虚拟式比较正式，多用于书面语中，其假想性很强，实现性很小。如：

If I were to do it, I would do it another way. 要是我来做这件事，我会用另一种方法。

If he were to come tomorrow, I would speak to him about it. 假如明天他来，我会跟他谈这个问题。

情态助动词用于虚拟语气

有不少情态助动词也可用于虚拟语气。如： May you live a long and happy life. 愿你长寿幸福。（may只用于表示愿望）

If there were no friction, an automobile could not move. 没有摩擦力，汽车就不能开动。

But for your help, we couldn’t have succeeded. 要不是你的帮助，我们是不会成功的。

If computers had not been invited, many problems on space flight could not have been solved. 如果没有发明计算机的话，宇宙飞行的许多问题就不可能解决。

were， had， should等置于主语之前

在书面语中，条件从句可以不用连词if，而将谓语中的过去式were，had或 should 等移至主语之前。如： Were you in my position, what would you do? 假如你处在我的位置，你会怎么做？

Were he to leave today, he would get there by Friday. 如果他今天动身，星期五前会赶到那儿。

Had some work been done, energy would have been applied. 如果做了一定量的功，就一定消耗了能量。 Had they time, they would come to see you. 如果他们有时间，他们就会来看你。

Should it rained tomorrow, the meeting would be postponed. 万一明天下雨，会议就会延期。

Should he come, he would be able to examine the trial run of the machine. 如果他来，他就能检验这台机器的试车情况了。

条件从句与结果主句所表示的时间不一致

(1) 当条件从句与结果主句所表示的时间不一致（如一个是过去发生的，一个是现在发生的）时，虚拟语气的形式应作相应的调整。如： If you were in better health, we would have asked you to come. 如果你身体好一些，我们早就请你来了。

If we had consulted him on the question yesterday, we should know what to do now. 假如昨天我们向他请教了这个问题，现在就知道该怎么办了。

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。 (2) 如果条件从句用if I were．．．，结果主句则可用任何时间的虚拟形式。如： If I were not busy, I would have come. 假如我不忙，我就会去的。（were表过去）

虚拟语气在含蓄条件句中的用法

(1) 条件暗含在短语中。如：

We didn’t know his telephone number; otherwise we would have telephoned him. 我们不知道他的电话号码，否则我们就会给他打电话。（暗含条件是otherwise） Without your help, we wouldn’t have achieved so much. 没有你的帮助，我们不可能取得这么大的成绩。 （暗含条件是介词短语without your help）

But for your help, I would not have succeeded in the experiment. 如果没有你的帮助，我的实验就不会成功。（暗含条件是but for your help） It would cause great trouble not to lubricate the bearing immediately. 不立即润滑轴承就会引起很大的故障。

（暗含条件是not to lubricate the bearing immediately） Alone, she would have been terrified. (2) 条件暗含在上下文中。如： I would not have done it that way.

我是不会那么做的。（可能暗含if I were you）

I was busy that day. Otherwise I would have come to help you. 我那天很忙。否则我会来帮你的。（可能暗含if I hadn’t been so busy.） You might come to join us in the discussion. 你可以参加我们的讨论。（可能暗含if you wanted to） I would have bought the DVD player.

我是会买下那台影碟机的。（可能暗含if I had the money）

But for the storm, we should have arrived earlier.

要不是碰到暴雨，我们还会早些到。（可能暗含if it had not been for the storm）。

省去结果主句的非真实条件句

非真实条件句若省去结果主句，则常表示一种不可能实现的愿望。这种条件句常用if only来引导。如： If I could see him once我只要再见到他一次就好了。 If only he were here. 如果他在这儿就好了。

If only I hadn’t done that. 我要是没做那事就好了

If only I had more time to think about it. 我要是有更多的时间考虑这个问题就好了。 If only you would take my advice. 你如果听我的意见就好了。

If only she didn’t drive so fast! 她要是别开那么快就好了。

不用if引导的条件句

非真实条件句的条件从句除用if引导外，还可用when, unless, lest, as if, for fear, in case, on condition that等词语来引导。如：

The government prepared to award them when the experiment should be completed. 已准备在实验完成后嘉奖他们。

Steel parts were usually covered with grease lest they should rust. 钢部件通常涂有油脂以免生锈。

Unless I were well, I wouldn’t be at work. 除非我好了，否则我不会去上班。

The electric current flows through a conductor as if it were a fluid. 电流好像液体般地流过导体。

He handled the instrument with care for fear (that) it should be damaged. 他小心地摆弄那仪器，生怕把它弄坏。

Take some more money with you in case you should need it. 多带点儿钱以备急用。

He can use the car on condition that he should return it tomorrow. 如果明天车能还回来，他就可以把车借去。

Suppose you were given a chance to get the job, would you accept? 假如你有机会得到那份工作，你会接受吗？

但要注意：与if一样，上述词语所引导的条件从句也可用直陈语气，表可能实现或发生的事。

虚拟语气-虚拟语气在从句中的用法

主语从句中的用法

(1) 在以it为形式主语的复合句中，虚拟语气在主语从句中表示建议、要求、命令等，谓语动词用should be型或be型虚拟式，在美国英语中常用be型虚拟式。如： It’s natural that she should do so. 她这么做是很自然的事。

It is essential that we should tell her the news. 我们有必要告诉她这个消息。

It is important that we should make full use of our mineral resources. 对我们来说，充分利用我国的矿产资源是重要的。

It is strange that the result of the experiment should be unsatisfactory. 奇怪的是实验结果竟然如此令人不满意。

It is desired that we should get everything ready by tonight. 希望一切在今晚准备好。

It was arranged that Mr Sam should go and help Bettie. 他们作了安排，由萨姆先生去帮助贝蒂。

(2) 主句的谓语为某些动词的被动语态，常用在It is (was) desired (suggested，settled，proposed， recommended，requested，decided，etc.) that...句型中。

It is suggested that the question should be discussed at the next meeting. 有人建议在下次会上讨论这个问题。

It is vital that he should be warned before it is too late. 在还不太晚的时候警告他是非常必要的。

It has been decided that the sports meet should be postponed till next Friday. 已决定运动会延期到下星期五。

It was requested that a vote (should) be taken. 有人要求进行表决。

在宾语从句中的用法

(1) wish的宾语从句中的谓语动词形式 ① 动词的过去式表示对现在情况的假设。如： I wish prices would come down. 我真希望物价会下降。

I wish you would stop asking silly questions. 我希望你不要再问这种愚蠢的问题。 I wish I knew his address. 可惜我不知道他的地址。 I wish we could go with him. 我们要是能跟他一起去该多好。

② had+过去分词表示对过去情况的假设。如： I wish I had known it before. 我真希望我预先知道这件事。

He wishes he hadn’t been rude to his parents. 他真希望他没有对父母无礼。

She wished that she had stayed at home. 她想那时要是留在家里就好了。

I wish I could have been there yesterday. 要是我昨天到过那里该多好。

(2) would rather等的宾语从句中的谓语动词形式

用would rather(=would sooner)和would(just)as soon(=would sooner)等表示愿望，但其宾语从句常用虚拟过去式。如： I would rather you came tomorrow than today. 我宁愿你明天来，而不是今天。

I could do it myself but I would sooner you did it. 我自己也可以做，但我宁愿你去做。

I would rather you had told me the truth. 我倒想你本该把事实告诉我。

(3) suggest等的宾语从句中的谓语动词形式

① 用should＋ 动词原形或只用动词原形的that 从句，作为demand, order, prepose, request, require, suggest,arrange, insist, command, desire, advocate, maintain, urge, direct, move, prefer, arrange, recommend等词的宾语。如： The expert proposed that TV should be turned off at least one four every day. 专家提议每天至少应该关掉电视一个小时。

The board recommended that the company should invest in the new property. 董事会建议公司投资新的房地产。

The committee has given instructions that the manager should fly to New York. 委员会已发出指示，要经理飞往纽约。

Secretary of War Edwin M. Stanton ordered that James Van Metre should be released. 陆军埃德温·Ｍ·斯坦顿命令将詹姆斯?范?米特释放。

He asked that the arrangements be made to help them finish the work. 他要求做好安排，帮他们完成工作。

Experiments demand that accurate measurements be made. 实验要求做到准确的计量。

She insisted that we take up the matter at the meeting. 她坚持要求我们在会上谈这个问题。

② 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. 我万没想到他会拒绝。

I had not expected that things should turn out like this. 我没料到事情的结果竟是这样。

在表语从句中的用法

虚拟语气也可用在表语从句中。这种从句由that（可省略）所引导，其谓语是 should ＋动词原形。句子主句中的主语常常是suggestion, proposal, idea, motion, order, recommendations, plan, impossibility, possibility等名词。如： His suggestion was that everyone should have map. 他的建议是每人发一张地图。

My idea is that the electronic device should be tested at once. 我的意见是这一电子器件要立即试验。 在主句中作主语的名词常见的有：

advice， aim， desire， idea， insistence， motion， necessity， order， plan， proposal， recommendation， regulation，

requirement， suggestion， wish等。

虚拟语气在同位语从句中的用法

当与同位语从句同位的是suggestion等表示建议、计划、命令等的名词时，从句的谓语动词用should+动词原形，美国英语中常用动词原形。

They made the request that the problem should be discussed as soon as possible. 他们要求尽快讨论这个问题。

He gave orders that the work should be started at once. 他命令工作马上开始。

The proposal that he (should) be dismissed was supported at the meeting. 大会对开除他的提议表示了支持。

虚拟语气在状语从句中的用法

(1) 虚拟语气在让步状语从句中的用法

① 由连接词whether, if, even if/though, whatever, so ong as 引导的状语从句，其谓语可用虚拟语气，即其谓语用动词原形。如： Whether the figures be accurate or not, they have to be rechecked. 不管那些数字准确与否，都得重新核对。

The earth is powerful magnet and all magnets behave the same whether they be large or small. 地球是一个强大的磁体，而所有的磁体无论大小其作用都是一样的。

They have decided to build a reservoir, whatever the difficulties may be. 他们决心建造一座水库，不管有多少困难。 I won’t let you in whoever you may be. 无论你是谁我都不让进去。

However hard the task may be, we must fulfill it on time. 不管任务多么艰巨，我们必须按时完成。

If the defendant be found guilty, he shall have the right of appeal. 如果被告被判有罪，他有权上诉。

② 倒装的让步状语从句中的虚拟语气。如： Come what may，we will go ahead. 不管怎样，我们一定要前进。

However hard it may rain，we shall have to go. 无论雨多大，我们都得走。

(2) 虚拟语气在方式状语从句中的用法

以连接词as if引导的状语从句（谓语形式与wish后的宾语从句相同，be在第一、三人称可用was或were）。如： You speak as if you had really been there. 你说的好像你真的去过那里。

Light often behaves as though it were made of particles. 光的性状，常常有点儿像由粒子组成的。 He spoke to me as if I was(were)deaf. 他跟我说话时就好像我是聋子似的。 (3) 虚拟语气在目的状语从句中的用法

以lest, for fear that 和in case 引出的状语从句（谓语多用should加动词原形构成）。如： Batteries should be kept in dry places lest electricity should leak away. 电池应放在干燥的地方，以免漏电。

He handled the instrument with care for fear that it should be damaged. 他小心地弄那仪器，生怕把它弄坏。

I’ll keep a seat for you in case you should change your mind. 我给你留一个位子，说不定你会改变主意。

在it ‘s time后的定语从句中的用法

虚拟语气还可用在定语从句中，这种从句常用在it is (high, about) time (that)．．．句型中。定语从句常用虚拟过去式。如： It is time we started. 我们该出发了。

It is time we set to work. 我们该着手工作了。 It is time we left. 我们该走了。

It is time we should leave. 我们该走了。

It is time I were off. 我该走了。

It’s high time the weather improved. 天气真该好起来了。

但要注意：位于time之前的high起着强调“为时稍晚”的作用。

虚拟语气-真实条件句和非真实条件句中介词

虚拟语气用来表示说话人的主观愿望或假想，所说的不一定是事实，可能有时甚至与事实相反。真实条件句用陈述语气，因为句子表示的假想是真实的或有可能实现的；而非真实条件所表示的是假设的或实现可能性不大的情况，故采用虚拟语气。

有时，在实际应用中真实条件或非真实条件不以条件从句形式出现(即带if的从句)，而可以通过介词或介词短语来表示，我们可以称之为含蓄条件句(sentences of implied condition)。下面，就和大家共同探讨含蓄条件句里的真实条件句和非真实条件句中介词或介词短语的运用：

一、 介词或介词短语在真实条件句中的运用：with, in case of, in the event of 等通常用在真实条件句中，要用陈述语气。

1. with

With a little assistance, Alexander will succeed. (with=if he is given，表示真实条件，本句用的是陈述语气。)

2. in case of 万一

In case of fire, please dial this number. (in case of fire=if a fire breaks out，表示真实条件，本句用的是陈述语气。)

3. in the event of 如果„„发生，万一

In the event of bad weather, we shall/will have to cancel the picnic. (in the event of bad weather=if the weather turns out bad, 表示真实条件，本句用的是陈述语气。)

二、介词或介词短语在非真实条件句中的运用：without, but for, in the absence of, under, but that等通常用在非真实条件句中，要用虚拟语气。

1. without

I would have failed in the examination without your help. (without=if it had not been for，表示同过去相反的非真实条件句，本句用的是虚拟语气。)

2. but for 要不是

But for your timely rescue, the boy would have drowned. (but for=if it had not been for, 表示同过去相反的非真实条件句，本句用的是虚拟语气。)

3. in the absence of 缺乏„„时，当„„不在时

In the absence of the keeper, the warehouse would have been burned down. (in the absence of the keeper=if the keeper had been absent, 表示同过去相反的非真实条件句，本句用的是虚拟语气。)

4. under

We might have done better in our research under more favorable conditions. (under= if we had worked under, 表示同过去相反的非真实条件句，本句用的是虚拟语气。)

5. but that 若非

But that your guidance, we should/would fail. (but that=if it were not for, 表示同现在相反的非真实条件，本句用的是虚拟语气。)

总之，可以替代if并构成含蓄条件句的介词和介词短语还有很多，我们在学习过程中，要注意观察和辨析，掌握好介词和介词短语在含蓄条件句里的真实条件句和非真实条件句中的运用。

虚拟语气-含蓄虚拟条件句的七种表现形式

所谓含蓄虚拟条件句即指将条件从句隐藏在上下文一定的短语中的一类条件句，其主要用法及表现形式可归纳如下：

1. 将条件隐含在不定式短语中

I would write to her, but I don’t know her address. 我会给她写信的，就是不知道她的地址。(=If I knew her address, I would write to her. But„)

To have studied harder, you would have passed the examination. 你学习更用功些，你早就考及格了。(=If you had studied harder,

you„)

2. 将条件隐含在分词短语中

Born in better times, he would have been a scholar. 如果出生在好时代，他早就成为学者了。(=If he had been born in better times, he would„)

Failing this time, what would you do？ 假若这次失败，那你怎么办？(=If you failed this time, what would„)

Walking alone in the dark, Mary would be terrified. 要一个人单独在黑暗中行走，玛丽会感到十分害怕。(If Mary walked alone in the dark, she„)

3. 将条件隐含在介词短语中

But for your help we couldn’t have succeeded in the experiment. 如果没有你的帮助，我们的实验是不会成功的。(=If it hadn’t been for your help, we„)

In different circumstances, I would have said yes. 在不同的情况下，我就会同意了。(=If circumstances had been different, I would„)

4. 将条件隐含在名词短语中

Any person who had behaved in that way would have been dismissed. 任何人这样做了都会被开除。(=If any person should behave in that way„, he would„)

A few hours earlier, and you would have seen the famous writer. 要是你早来几个小时，你就见到这位著名的作家了。(If you had come a few hours earlier, you„)

5. 将条件隐含在某些连词中

I didn’t know that he was a cheat, or else I wouldn’t have believed him. 我不知道他是个骗子，不然我也不会相信他了。(or else=if I had known he was a cheat))

I’m really very busy, otherwise I would certainly go there with you. 我真的是太忙了，不然我就会同你一道去了。(otherwise=if I were not so busy)

6. 将条件隐含在定语从句中

Anyone who had seen that painting might have taken it for a photo. 凡是看过那画的人，都可能把它看成是照片。(=If anyone had seen that painting„)

7. 将条件隐含在一定的上下文中

You might stay here forever. 你可以永远待在这儿。(=If you wanted to, you might„)

Don’t bother to read all these papers. It would take too long. 不要费事看所有这些文件了，那会花太多时间。(=„If you read all these papers, It would take too long)

虚拟语气-四类省略的虚拟条件句型

一、省略连词if

有时可将条件从句的连词if省略，但此时应用倒装句型，即将从句中的were, should, had 等提到句首：

Were I Tom, I would refuse. 如果我是汤姆，我会拒绝。

I will go, should it be necessary. 假若有必要，我会去的。

Had it not been for the bad weather we would have arrived in time. 若不是天气坏，我们就准时到达了。

【注】① 若条件从句为否定句，否定词not应置于主语之后，而不能与were, should, had 等缩略成Weren’t, Shouldn’t, Hadn’t而置于句首。

② 有时省略if后提前的had不是助动词：

Had I time, I would come. 假若我有时间，我会来的。(=If I had time„)

二、省略条件句的主语和其后的动词be

若主从句主语一致，且谓语部分包含有动词be，通常可将主语和动词be省略：

If repaired earlier, the tractor would not have broken down. 要是早点儿修一下，拖拉机就不会抛锚了。(=If it had been repaired earlier„)

三、省略“it+be”

If necessary, I would send more farm-hands to help you. 如果需要的话我会派更多的民工去帮你。(=If it was necessary, I would„)

四、省略整个条件从句

这样的省略通常需要借助一定的上下文，即省略条件从句后，所剩下的主句的意思在一定的上下文中意思是清楚的：

I might see her personally. It would be better. 我可以亲自去看她，这样好一些。(=„If I saw her personally, it would be better.)