Verified answer

1. I would have visited Sarah yesterday if I had known that she was ill.
2. If you had gone to Paris with me last month, you would have seen the Eifel Tower too.
3. We wouldn't have got wet if you had taken the umbrella.
4. If Mum hadn't opened the windows, our room wouldn't have been full of mosquiotoes.
5. Nick wouldn't have been so tired this morning if he had gone to bed early last night.