Third conditional — denkbeeldig verleden
If + past perfect, would have + voltooid deelwoord If I had known, I would have come. — Als ik het had geweten, was ik gekomen.
In spreektaal: If I'd known, I'd have come. (Let op: 'd = had na if, would in de hoofdzin.)
Mixed conditional — verleden oorzaak, gevolg nu
If I had taken that job, I would be rich now.
Nooit would in de if-zin: If I would have known.