虚拟语气的几种用法
1．错综时间条件句
虚拟语气通常用于含条件状语从句的主从复合句中。

条件状语从句中表示与现在、过去或将来事实相反的虚拟语气比较容易掌握，但绝不可把它们当作一成不变的数学公式一样对待。

就是说，不能只单纯背语法条条框框，而应充分理解句子锁定的语言环境。

有时从句动作与主句动作发生的时间不一致。

这时就要根据各自表示的时间概念加以调整。

如：
If he had taken my advice, he would be much better
now．（从句与过去事实相反，主句与现在事实相反。

）
2．含蓄条件句
有时假设的情况并不是以条件状语从句的形式表示出来，而是通过一个介词(如：without; butfor)引出的短语，一个连词（如：but; or; otherwise）引出的从句或其它方式来表示。

如：Without your help, we couldn’t have finished the job in
time．(Without your help＝If you hadn’t helped us)
He could have given you more help, but he was busy．(but
he was busy＝if he had not been busy)
3．倒装句
如从句中有were, had或should，则可以省去if, 并将were,
had或should提前到句首，构成部分倒装。

如：
Were I to be young again, I would study
medicine．(从句正常语序为：If I were to be young again)
Had you not left so early, you might have missed the
train．(从句正常语序为：If you had not left so early)
4．错综语气
有时从句用虚拟语气，主句却用陈述语气或祈使语气。

如：
If there should be an earthquake, what will you
do﹖ (从句用虚拟语气，主句用陈述语气。

)
Ask her to leave a message if she should
come．（从句用虚拟语气，主句用祈使语气。

）
5．It is (high) time (that)句型
这个句型往往用“过去时”形式表示“现在”的动作，有时也用“should＋动词原形”。

如：It’s high time (that) we began to work．
I think it’s time (that) you made up／should make up your
mind．
6．主句中含有suggest, suggestion, propose, proposal, insist,
order, demand, request等词时，从句谓语部分常用“(should)＋动词原形”。

如：
She suggests that they (should) go there right away．
Her suggestion is that they (should) go there right
away．
It is suggested that they (should) go there right away．
7．so that和in order
that引导的目的状语从句常由“can／could／may／might＋动词原形”构成；在否定结构中，常由“shouldn’t＋动词原形”构成从句的谓语形式。

如：
Speak clearly so that they may／might understand you．
He took a taxi to the station inorder that he should not
miss the train．
8．would rather后的宾语从句
表示现在和将来的时间概念时，从句动词用过去式，表示过去的时间概念时，从句动词用“had ＋过去分词”。

如：
I’d rather you came here this Saturday．
I’d rather I had seen the professor yesterday．
非If条件从句表示的虚拟条件
一般来说，在表达虚拟条件时，通常用if条件句，其基本句式为：
if条件句＋主句。

主、从句中的时态也是根据时间的不同而不同并相对固定。

如：
If I were you, I would not go there with him．
我要是你的话，就不会和他一起去那儿。

（和现在事实相反）
If you had come here earlier yesterday, you could
have met him．
假如你昨天早些来的话，你就能见到他了。

（和过去事实相反）
但是有时却不用if条件句来表示条件，而用其它方式。

在各类考试中不断出现这方面的考查。

如2001年上海春季高考试题中就有这样一道选择题：
He hesitated for a moment before kicking the ball
otherwise he ＿＿＿＿a goal．
A．had scored B．scored C．would score
D．would have scored
本题意思是：他犹豫了一会儿才踢出这个球，不然他就进球了。

其真实含义是：他没有进球。

“进球”是虚拟的，但“犹豫了一会儿”是真实的。

所以本题还可理解为：如果他不犹豫的话，他就进球了。

因此，这里由“otherwise”代替了一个条件句。

从hesitated的时态可以判定本题表示的是和过去事实相反的含义，故本题答案为D。

本题中用otherwise表示条件，这种情况语法上称为“含蓄条件句”。

具体说来，“含蓄条件句”有下列几种情况：
一、用介词短语表示条件。

这些介词通常有：without，but for （要不是）等。

如：
Without air and water (If there were no air and
water), all living things on the earth would die．
地球上如果没有空气和水，一切生物都将死亡。

But for the car accident (If there had not been the
car accident), we would have arrived there much earlier．
要不是因为车祸，我们早就到了。

二、用连词or, otherwise, but, once, though等表示条件。

如：
He was taken to hospital at once yesterday,
otherwise ／or he would have died already．＝If he had
not been taken to hospital at once yesterday, he would
have died already．
昨天他被立即送到了医院，要不然他早就死了。

I would have attended the important meeting, but I
was too busy then．＝If I had not been too busy then, I
would have attended the important meeting．
要不是当时太忙，我就参加那个重要会议了。

Einstein cared little for money, though he could
have been very rich．＝If Einstein had cared much for
money, he could have been very rich．
如果爱因斯坦很在乎钱的话，他已经很富有了。

Once lost, it would be very hard to find again．＝If
it were once lost, it would be very hard to find again．
一旦失去了，就不容易再找回。

三、用分词短语表示条件。

如：
Given more time, we could have done the task much
better．＝If we had been given more time, we could have done the task much better．
如果再给我们点时间，我们会做得更好。

Supposing it should happen, we would have to stay at
home．＝If it happened ／should happen ／were to happen, we would have to stay at home．
假使那件事发生的话，我们就不得不呆在家里了。