有时主句和从句的谓语动词指不同的时间，这时需要用混合虚拟语气。一般来说，在这种情况下，主从句谓语动词指代的时间不同，所以我们又可以错综时间条件句，在这种虚拟情况，动词形式应根据实际情况灵活使用，在做这些题目时候尤其要注意每道题目的提示语：时间状语。绝大多数情况下，从句或者主句都有相关的时间状语，这是我解题的关键。
If youthat late movie last night, you
wouldn’t be so sleepy.
A. haven’t watched
B. didn’t watch
C. hadn’t watched
D. wouldn’t have watched答案选C。
Many dead would now be alive if they have not attempted to returnfor something.
Had Paul received six more votes in the last election, he would beour chairman now.
混合虚拟语气还有一种情况就是事实和虚拟假设的混合句，这样的句子不仅仅是时间的不同，而重要是事实和假设的混合。
I would have gone to visit him in the hospital had it been at allpossible, but I was fully occupied the whole of last week.
该句前半部分是假设虚拟，而后半部分是事实的陈述。
Your math instructor would have been happy to give you a make-upexamination had you gone and explained that your parents were ill at the time.
该句前半句用的是假设虚拟，后半句主句也用的是假设虚拟(如果你去并且解释的话)，但是后半句的从句用的是事实语气，因为“父母病了”是客观事实，故不需要用虚拟形式had been。
考博英语语法：含蓄虚拟条件句
含蓄条件句是指句中没有明显的虚拟条件句，而是利用其他手段来暗示存在虚拟条件。但是这类隐含式虚拟条件句往往都可以转化为if引导的条件句。常来表示含蓄虚拟条件的手段有：
(1)介词或介词短语，如but for, but that, without, in
case of, under more favorable condition等。
the leadership of the party, we could not be living a happy
today.=If there hadn’t been the leadership of theparty, we could not be living a happy today.
A. In spite of
B. But for
C. Because of
D. As for答案选B。
But that she was afraid, she would have said no.
(2)连词，如：so that, unless, in case, supposing,
lest, provided(倘若……)，for fear
that(唯恐)，in order that, on
condition that, if only(要是……就好了)等。
She listened carefully in order that she might discover exactly whathe wante
D.=if she listened carefully ,she might discover exactly what hewante
D.
If only I had more money, I could buy a car.
(注：lest, for fear that和in case引起的从句中谓语动词多用should+动词原形，但可以不用虚拟语气，而用动词的陈述语气形式。)例如：
The foreign teacher spoke slowly in case we misunderstood him.这位外籍教师说得很慢以免我们听不懂。
Care must be taken in using this method lest overflow should occur.在使用此法时要小心谨慎，以免会发生溢流现象。
(3)通过上下文及内在含义，句中往往有but, otherwise,
unfortunately等类似转折词。
I thought the childrenwhen we returnedhome, but they were still awake.
A. were sleeping
B. would be sleeping
C. had been sleeping
D. would sleep选择B。
(4)形容词及其比较级
A more careful person would not have made so many mistakes.
A less conscientious man wouldn’t have triedso hard to get this job done.
(5)分词短语
Having known in time, we might have prevented the accident.
Born ten days earlier, the boy could have seen his late father.
(6)动词不定式短语。一般intended/meant/hoped/wished/planned或was/were+不定式完成式或had
intended/meant/planned/hoped/wished/+不定式一般式表示虚拟。
I intended I should call on you, but I was busy at that time.
To hear him speak French, you would take him for an Englishman.
She would be stupid not to accept his invitation.
It would be easier to do it this way.
(7)名词短语和名词+and结构
A judicious man would not have committed suicide.
A diligent student would have worked harder.
(8)独立主格结构
All things considered, the price would be reasonable.
(9)定语从句
Anyone who had been in your position would have done the same.
A nation, which stopped working, would be dead in a fortnight.
(10)情态动词完成式暗示虚拟语气：
I should have called to make an airline reservation, but I didn’t.
The porter ought to have called the fire-brigade as soon as he sawthe fire in the stock, which went up in smoke.
(11)动词原形表示虚拟
动词原形直接用在句子中也被看作是一种虚拟，最常见于正式文体中，动词原形一般用在条件从句中，有时倒装置于句首，同时这种用法也常见于独立句中表达愿望。
God bless you!
All magnets behave the same, be they large or small.
She’ll be sixteen years odd, com May.(comeMay =when May come).
If that be so, we shall take action at once