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Third conditional: If I had known…
B2 B2 grammar · lesson 3 of 21
The third conditional lets you imagine a different past and its result. You use it to talk about regrets, mistakes and lucky escapes.
Rule
We use the third conditional for situations in the past that did not happen. We imagine them and their results. The past cannot change, so the situation is unreal.
Compare: the second conditional (B1) is about an unreal present or future; the third conditional is about an unreal past.
Form
| If-clause | Result clause |
|---|---|
| If + had + past participle | would have + past participle |
| If I had known, | I would have told you. |
| If she hadn’t missed the bus, | she wouldn’t have been late. |
You can also start with the result: I would have helped if you had asked. No comma is needed in that order. Instead of would, you can use could have (ability) or might have (possibility).
If I had studied more, I would have passed the exam.
If we had left earlier, we wouldn’t have missed the train.
Tom would have come to the party if he hadn’t been ill.
If you had asked me, I could have helped you.
If it hadn’t rained, we might have gone to the beach.
What would you have done if you had lost your passport?
If Lucy hadn’t taken that job, she wouldn’t have met her husband.
Short forms
In speech, both had and would become ‘d: If I‘d known, I‘d have told you. Look at the next word: ‘d + past participle = had; ‘d + have = would. People also say would’ve /wʊdəv/.
Common mistakes
✗ If I would have known, I would have called.
✓ If I had known, I would have called.
✗ If she had told me, I would helped her.
✓ If she had told me, I would have helped her.
✗ If we had took a taxi, we would have arrived on time.
✓ If we had taken a taxi, we would have arrived on time.
✗ I would of gone if I had had time.
✓ I would have gone if I had had time.