The third conditional imagines a different past: something that did not happen, and what would have happened if it had. The “if” clause uses the Past Perfect, the result clause would have + past participle. It is often used to express regret or criticism.
Form
| Structure | Example |
|---|---|
| If + past perfect, would have + past participle | If I had studied, I would have passed. |
| would have + past participle + if + past perfect | She would have come if she had known. |
When to use it
- Regret: If I had listened to you, I wouldn't have made that mistake.
- Criticism: If you had called, we would have helped.
- Imagining other outcomes: If he had trained harder, he would have won.
- Excuses and explanations: I would have come if I had been free.
Examples
- If I had known, I would have helped.
- If she had left earlier, she wouldn't have missed the train.
- What would you have done if you had lost your job?
- We would have won if we had played better.
- If it hadn't rained, we would have had a picnic.
- I wouldn't have said that if I had known.
Common mistakes
- “Would have” in the if-clause: If I would have known → If I had known.
- The past simple instead of the past perfect: If I knew, I would have helped → If I had known…
- Mixing time: for a past condition with a present result use a mixed conditional.