条件句用法归纳
conditional | If clause | Main clause |
zero | present simple | present simple |
1st | present simple | will do |
2nd | past simple | would/could/should/might do |
3rd | past perfect | would/could/should/might have done |
Zero conditional 第零条件句
又称“真实条件句”，表示具有普遍真实性的事情，用语表述某个动作产生的直接结果。
如：If you heat water, it boils.
When you put a rock in water, it sinks.
If you walk too fast at high altitude, you get really short of breath.
祈使句可以用于条件句中，表示“如果…, 则某人应该做…”
如：If the baby cries, give her some milk.
If you’re cold, put on a coat.
First conditional 第一条件句
又称“将来真实条件句”，使用if描述某种可能会在未来产生结果的现实动作，即如果现在…，那么将来就会…
如：If I don’t move, he’ll go away.
If Kate gives me some help, I’ll finish my work in an hour.
You won’t meet anyone if you don’t go out.
Second conditional 第二条件句
又称“虚拟条件句”，用于表述现在的虚拟情况。if从句描述不太可能发生的事或虚拟的动作，主句描述不太可能产生的结果。
如：If we were rich, we’d buy a bigger house.
I’d call her if I knew her number.
Who would you invite if you won a holiday for two?
Third conditional 第三条件句
又称“过去情况的虚拟条件句”，用于表述过去的虚拟情况，描述与事实相反的过去情况，即“要是…，就…了”或“要是…，就不会…了”
如：If we had left earlier, we would have caught the train.
If I had studied harder, I could have been a doctor.
If you hadn’t gone to the disco last weekend, you wouldn’t have met your new boyfriend.
Mixed conditionals 混合条件句
一般用于表述与事实相反的过去情况在现在产生的虚拟结果。比较：
If I had found a holiday job, I would have earned some money.（第三条件句）
If I had found a holiday job, I would have plenty of money now.（混合条件句）
再如：If I hadn’t eaten too much last night, I wouldn’t be feeling ill today.
(第三条件与第二条件句的混合)
If I liked horror films, I would’ve gone to see ‘Nightfright’ with。you.
(第二条件与 第三条件句的混合)
Tips: 时态后退一步
虚拟语气主要通过动词时态的变化来体现
一般现在时do 退➡️ 一般过去式 did
现在完成时have done 退➡️ 过去完成时 had done
一般过去式did 退➡️ 过去完成式had done
一般将来时 will 退➡️ 过去将来时would
过去将来时would 退➡️ 过去将来完成时 would have done
情态动词can/may/shall 退➡️ could/might/should