虚拟语气：条件句
表示与事实相反，或不太可能发生的假设。
if I were … / if I had done …
要点
- 与现在事实相反：if 从句用过去式（be 一律用 were），主句 would/could/should + do。
- 与过去事实相反：if 从句用 had done，主句 would have done。
- 与将来事实相反：if 从句用 were to do / should do，主句 would do。
- 省略 if 时把 were / had / should 提到句首：Were I you, …
- 含蓄条件句用 without、but for 代替 if 从句。
- 从句与主句的时间不一致时各自退格（混合虚拟）：从句说过去、主句说现在，就一边 had done、一边 would do。
- if it were not for…（现在）／ if it had not been for…（过去）＝「要不是」，退格看它说的是什么时候。
- 与将来事实相反、且认为可能性极小时，从句三种写法都成立：did / were to do / should do。
例句
If I were you, I would take the job.
如果我是你，我会接受那份工作。
If he had come yesterday, he would have met her.
如果他昨天来了，就能见到她了。
If it should rain tomorrow, we would stay at home.
万一明天下雨，我们就待在家里。
Were I you, I would not give up.
我要是你，就不会放弃。
If you had taken my advice, you would not be in trouble now.
你要是听了我的建议，现在就不会惹上麻烦了。
But for your help, I would have failed.
要不是你帮忙，我早就失败了。
易错提示
- 虚拟条件句里 be 一律用 were，不用 was。
- 从句与主句的时态是错开的，别两边都用 would。
- 提 were / had 到句首时 if 已经省掉，不能再写 if were I you。
- 「If I would have time」是错的 —— would 只出现在主句，从句里不堆 would。