Ответ:
2. It is a pity that you will be so busy in the evening and cannot help me.
3. What would you do if a building started a fire?
4. If not for his work, he would be able to become your guide in St. Petersburg with pleasure.
5. I do not like skiing, otherwise I am. perhaps the countryside would have traveled with you on such a wonderful winter day.
6. It is a pity that you then did not understand how wrong you were.
7. You won’t understand anything if you don’t listen to me carefully.
8. If I knew that you were at home last night, I would have rushed to you for a moment to chat and have a cup of tea.
9. If he had been even a little wiser, he would not have squandered his entire fortune by gambling.
10. I did not blame him. In his place, I would do the same.