1 I wouldn’t have married him if I had known what he was like.
2 I wouldn’t have hired a car if I had know how expensive it was.
3 If we had got to the cinema earlier, we would not have missed the start of the film.
4 If I had been born a year earlier, I would have had to do military service.
Third Conditional: main clause - would have V3/ Ved, if clause - Past Perfect.