1. If he had come in time, this wouldn't have happened.
2. I wish you weren't busy in the evening and could help me. (Намного лучше просто сказать I wish you weren't busy in the evening, потому что на английском исходное предложение звучит странно)
3. What would you do if the fire started in the building?
4. If it wasn't for his work, he would be your guide in St.Petersburg.
5. If I liked skiing, I would go to the country in this wonderful winter day with you. (Если опустить фразу "чудесный зимний день" английское предложение будет красивее: If I liked skiing, I would go to the country with you.)
6. I wish you had realized how wrong you were.
7. You don't understand anything, if you won't listen to me carefully.
8. If I had known you were at home yesterday evening, I would have stopped by for a small chat and a cup of tea.
9. If he had been smarter, he wouldn't have wasted his entire fortune gambling.
10. I didn't blame him. If I were him, I would have done the same thing.
Небольшой совет на будущее: плохо переводить предложения с русского, ведь все языки разные, некоторые русские выражения на английском звучат нелепо. Лучше сразу думать на английском )