1. 非真实条件句中谓语动词的形式
1. 非真实条件句中谓语动词的形式
| 条件从句 | 结果从句 | |
|---|---|---|
| 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。
2. 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。
3. 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。
4. 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。
5. 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。
6. 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。
7. 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）
8. 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.
假如孤身一人，她会很害怕的。
(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）。
9. 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。
10. 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.
政府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。