Поставить глагол в скобках в Conditional 3 и 2
1.If he didn't ring me up, I(not to come)
2.If he(not to write) to me, I wouldn't have ansvered him.
3.If(to be) you, I would have apologised to her.

1.If he didn't ring me up, I wouldn't come.2.If he hadn't written to me, I wouldn't have ansvered him.3.If I had been you, I would have apologised to her.