第三条件句

第三条件句：if + had + 过去分词（过去完成时），would have + 过去分词。用来想象过去本可以有不同的结果——条件和结果都是不真实的，因为事情已经发生了。

缩写形式：If I'd known（had），I'd have come（would），I would've come。语速快时，would have 听起来几乎像 “would-ə”。

💡if 从句里的 'd 是 had（If I'd known）；结果部分的 'd 是 would（I'd have gone）。另外，would've 听起来像 “would of”，很多人因此拼错——书写时一定要写 would have。

1. 想象一个不同的过去——实际发生的情况正好相反

• If I had left earlier, I wouldn't have missed the train.

  如果我早点出门，就不会错过火车了。（我出门晚了，错过了火车）

• If Lan hadn't helped me, I would have failed the course.

  要不是阿兰帮我，这门课我就挂了。（但阿兰确实帮了我）

2. 对过去的事表示遗憾或责备

• If you'd told me it was your birthday, I'd have bought you a cake.

  你要是早告诉我那天是你生日，我就给你买蛋糕了。

• We would have won if we hadn't made so many mistakes.

  要不是我们犯了那么多错，我们就赢了。

3. 庆幸坏事没有发生

• If the neighbours hadn't smelled the smoke, the whole house would have burned down.

  要不是邻居闻到了烟味，整栋房子都会被烧毁。

• If you hadn't reminded me, I would have forgotten my passport.

  要不是你提醒我，我就忘带护照了。

结果部分可以用 could have + V3（= would have been able to，本来能够）或 might have + V3（= would perhaps have，本来也许会）代替 would。

• If we'd booked earlier, we could have sat together.

  如果我们早点订票，就能坐在一起了。（could have = would have been able to，本来能够）

• If she had applied, she might have won the scholarship.

  如果她当时申请了，说不定就拿到奖学金了。（might have = would perhaps have，本来也许会）

弄清每个分句说的是什么时间。说过去的分句 → had V3 / would have V3；说现在的分句 → 一般过去时 / would + 动词。两个分句说的是不同时间时，就构成混合条件句。

• If I had studied medicine, I would be a doctor now.

  如果我当初学了医，现在就是医生了。（过去 → 现在）

• If we hadn't moved to Da Nang, we wouldn't know each other.

  要是我们当初没搬到岘港，我们就不会认识彼此了。（过去 → 现在）

• If he were more organised, he wouldn't have forgotten the meeting.

  如果他做事更有条理，就不会忘了那个会议。（现在 → 过去）

• If I didn't have to work tomorrow, I would have stayed at the party longer.

  要不是明天得上班，我就在聚会上多待一会儿了。（现在 → 过去）

💡混合 1 的结果部分常有 now、today、still。看到 “now”，而 if 从句用的是 had V3，结果部分就用 would + 动词，不用 would have。

在正式英语中，可以省略 if，把 had 放到主语前面：Had I known = If I had known。否定形式是 Had … not + V3（不缩写成 Hadn't I…）。见“倒装”一课。

• Had we known the road was closed, we would have gone another way.

  要是我们早知道那条路封了，就会走另一条路了。

• Had she not called, I would have waited all night.

  要不是她打来电话，我就会等一整夜。（不说：Hadn't she called）

• ✗If I would have known, I would have come.

  ✓If I had known, I would have come.

  if 从句用 had + V3。“If I would have…” 在随意的口语中能听到，但不是标准用法。

• ✗If I knew you were in hospital, I would have visited you.

  ✓If I had known you were in hospital, I would have visited you.

  说的是过去的事 → had known。

• ✗We were late. If we had taken a taxi, we would arrive on time.

  ✓We were late. If we had taken a taxi, we would have arrived on time.

  结果也是过去的 → would have + V3。

• ✗If she had took the medicine, she would have felt better.

  ✓If she had taken the medicine, she would have felt better.

  had + 过去分词（taken），不用一般过去时。

• ✗If she had asked me, I would of helped her.

  ✓If she had asked me, I would have helped her.

  would've 听起来像 “would of”，但一定是 have。

• ✗If it had not rained, we would have play tennis.

  ✓If it had not rained, we would have played tennis.

  would have + 过去分词。