The 3rd conditional: What is it? How to use it!
Sam: Welcome to BBC Learning English. I'm Sam and today we're talking about the third conditional.
The third conditional is a little strange because we're talking about something that didn't happen in the past. Why would we do that? Well, because sometimes we want to imagine a different outcome.
A friend of mine came to visit me yesterday. It was a surprise, so when I opened my front door, I said:
If I'd known you were coming, I would have baked a cake!
Did I know she was coming? No. Did I bake a cake? No.
So I'm imagining a different result.
Because we're talking about an imaginary past, we use:
If + the subject + the past perfect, the subject + would have + past participle
And you can also swap those round: What would you have done if you'd known your friend was coming?