Third conditional

​unreal/ hypothetical situation in the past

if clause with if + past perfect. We form the main clause with would have + past participle.
If I had seen you, I would have greeted you.
If it had been sunny yesterday, we would have gone for a walk.
We would have gone for a walk if it had been sunny yesterday.

Third conditional

We can use might or may instead of would when the consequences weren’t certain.
If I hadn’t arrived late to the interview, I might have gotten the job.
If they’d stayed longer at the beach, we may have seen them.

Third conditional

We can use could instead of would to talk about hypothetical possibilities.
If my car hadn’t broken down, I could have taken you to the airport yesterday.
If they’d told us about the problem, we could have helped them