Third conditional

Definition

The third conditional imagines a different past condition and its unreal past result. It normally uses if + past perfect and would have + past participle.

Examples

• If we had left earlier, we would have caught the train.

  We did not leave earlier, so we did not catch the train.

• She would have called if she had known your number.

  She did not know the number, so the call did not happen.

• If the weather had been better, they might have stayed longer.

  Might have expresses an uncertain imagined result.

Third conditional vs. second conditional

Had + would refers to an unreal present or future situation. Had had + would have learned refers to a past opportunity that did not happen.

Would is not the only possible result modal

The result can use could have or might have when the meaning is ability, possibility or uncertainty rather than a definite imagined consequence.

• If the road had been open, we could have arrived before dark.

  Could have expresses an unreal past possibility or ability.

• If you had asked, they might have agreed.

  Might have keeps the imagined result uncertain.

Common mistakes