第三条件句

B1 Third conditional 36 / 50

概要

第三条件句谈论的是虚拟过去——那些没有发生的事。我们想象一个不同的过去，以及它带来的不同结果：If I had studied, I would have passed（但我当时没有学习，所以没通过）。

规则

第三条件句用来回顾一个过去的情况，并想象不同的结局，常用来表达遗憾、批评，或者“本可能发生却没有发生的事”。

这个句型分为两部分：

If 从句（条件）主句（结果）
if + 过去完成时（had + 过去分词）would / could / might have + 过去分词

If you had told me, I could have helped you.

这两部分可以调换顺序。主句在前时，不要加逗号：

  • If she had left earlier, she would have caught the train.
  • She would have caught the train if she had left earlier.

在结果部分选择正确的情态动词：

情态动词含义
would have确定的结果
could have过去的能力或可能性（“能够”）
might have可能但不确定的结果（“也许”）

两个分句都用过去时描述，但意思是不真实的：一切都和实际发生的相反。If I had known 的意思是我当时并不知道。

第二条件句与第三条件句——要看时间，而不只是看 if：

条件句时间例句
第二不真实的现在／将来If I knew her number, I would call her. （我现在不知道。）
第三虚拟过去If I had known her number, I would have called her. （我当时不知道。）

形式与结构

仔细留意缩略形式——‘d 可能表示两种不同的意思：

缩略形式完整形式位置
I’d studiedI had studiedif 从句（过去完成时）
I’d have studiedI would have studied主句

所以在 If I’d known, I’d have come 里，第一个 ‘d = had，第二个 ‘d = would。

否定式：

分句否定形式
If 从句if + hadn’t + 过去分词（If I hadn’t missed the bus…）
主句wouldn’t / couldn’t / might not have + 过去分词

疑问句：只对结果分句做倒装——情态动词（would / could / might）放在主语前面，wh-词（what、where、why）放在情态动词前面。if 从句保持陈述句语序：if I had told you，而不是 if had I told you。

  • Would you have believed me if I had told you? (Yes, I would. / No, I wouldn’t.)
  • Where would you have gone if the road had been closed?

wish / if only + 过去完成时表达对过去的遗憾（同样是虚拟过去的想法，只是没有 if 从句）：

  • I wish I had studied harder. （但我其实没有）
  • If only we hadn’t sold the house. （但我们其实卖了）

例句

English说明
If I had studied, I would have passed the exam.典型的遗憾——我没学习，所以没通过。
If you’d told me, I could have helped.could have = 我当时能做到，但没有机会。
If she had taken a map, she might not have got lost.might (not) have = 一种不确定的过去可能性。
He would have called you if he’d had your number.he’d had = he had had；注意语序，没有逗号。
If we hadn’t missed the flight, we wouldn’t have met them.否定条件，否定结果。
They could have won the match if they had trained harder.主句在前——注意 if 前面没有逗号。
I wish I had saved more money last year.wish + 过去完成时 = 对过去的遗憾。
If only I had listened to your advice!if only 让遗憾的语气更强烈。

常见错误

  • If I would have known -> If I had known——if 从句要用过去完成时，不能用 would have。
  • I would of helped -> I would have helped——would’ve 读起来像“would of”，但它其实一直都是 have。
  • If you told me, I would have come -> If you had told me, I would have come——表示虚拟过去，if 后面需要用过去完成时。
  • I would have went -> I would have gone——have 后面要用过去分词，不用一般过去时。
  • I wish I studied harder （谈论过去） -> I wish I had studied harder——表达对过去的遗憾要用过去完成时。

学习提示

  • 两部分，两个层次：if 部分用 had + done，结果部分用 would have + done。
  • 读出来是 would’ve / could’ve / might’ve——但绝对不要写成 would of。
  • 判断第二条件句还是第三条件句，看时间：不真实的现在 = 第二条件句；不真实的当时（一个已经结束的过去情况） = 第三条件句。
  • 过去的条件也可能导致现在的结果——这叫混合条件句（If I had taken that job, I’d be rich now），会在第 44 课讲到。