5.混合条件句

混合条件句又称错综条件句。若主句和从句所指的时间不一致，则主句和从句中应采用与具体时间相对应的虚拟形式。具体说来可能有下面几种情况。

(1)从句表示过去，主句表示现在。

If he had followed the doctor's advice at that time，he would be quite all right now．

他当时要是听了医生的忠告的话，现在就会平安无事了。

If it had rained last night，it would be very cold today．

假若昨晚下了雨的话，今天就会很冷了。

If I hadn't been walking the whole day，I wouldn't be so tired．

要不是我走了一整天，我就没有这么累了。

Had the weather been more favorable，the crops would be growing still better．

如果过去天气好一些的话，现在庄稼还会长得更好。

(2)从句表示过去，主句表示将来。

If we hadn't made preparations，we shouldn't dare to do the experiment next week．

如果我们还没有做好准备的话，我们下个星期就不敢做实验了。

If we hadn't got everything ready by now，we should be having a terrible time tomorrow．

如果现在一切还没准备好，明天情况就糟糕了。

If I had missed，and had shot too low，I was going to use this arrow on you．

如果我没有射中，或者射得太低，我就准备用这只箭射死你。

(3)从句表示将来，主句表示现在。

If we shouldn't' have an exam this afternoon，I would go shopping now．

要不是我们下午有考试的话，我现在就去逛街了。

(4)从句表示将来，主句表示过去。

If I were not to make a preparation for my experiment this afternoon，I would have gone to see the film with you last night．

要不是我要为今天下午的实验做准备的话，我昨晚就会跟你一起去看电影了。

(5)从句表示现在，主句表示过去。

If you were in better health，we would have allowed you to join them in the work．

如果你身体好一些，我们就会让你同他们一道干这工作了。

If he were not so busy，he would have come．

要是他不忙，他就来了。

If I were you，I wouldn't have missed the film last night．

如果我是你，我就不会错过昨天晚上的那部电影。

(6)有时主句或从句不用虚拟语气，表示这种情况实现的可能性虽然较小，但也不是完全没有。

If we buy the smaller one，we might have to change it in a few years'time for a bigger one．That would be a waste of money．

如果我们买更小的那个，过几年我们或许就要换一台大的。那样就是浪费钱了。

Ask her to ring me up if you should see her．

你万一见到她，请让她给我打个电话。

Should I be free tomorrow，I will come．

如果明天我有时间，我就来。

Should you have enough energy left after a day on the slopes，you can take a dip in the pool，work out at the gym or go dancing in one of the city's many hotels and clubs．(人教大纲版高二下第36页)

如果在山坡上玩了一天之后还有足够的精力，你还可以到游泳池里泡一泡，在体育馆里活动一下，或在城市里找一家宾馆或俱乐部跳跳舞。

Should he call what shall(should)I say?

她要是打电话来，我怎么说?

(7)should have done，would have done，could have done也可用在条件句中，表示与过去事实相反。should have done所表达的动作并非完全不可能发生，常和陈述语气连用。would have done为美国大众语。

Should the steamer have left port at noon，it will be passing through the canal now．

要是汽船正午离开了海港的话，想必现在这个时候正在经过运河。

If this sleeplessness would have been allowed to go on，she would have collapsed．

要是还让这种失眠继续的话，她或许早就已经崩溃了。