Third Conditional

Third Conditional

It is used to talk about an imaginary situation

Imaginary situation in the past, and it's imaginary result

Talks about something that didn't happen in the past

We use lots of short forms in third conditional

if + subject + past perfect, subject + would have + past participle

If I had known the trains were cancelled, I would have taken the bus

So in the if part, I and had are shortened to I'd

I and would are shortened to I'd

We also drop the h from have. So I would have becomes 'I'd've'