Ответ:

2. What were you talking about when I came in?

3. He didn't call you because his mobile phone wasn't working.

4. They were living in Sydney when their first child was born.

5. I'm sorry, were you watching that programme?

6. We were walking along the beach when we saw a snake.

7. She wasn't driving when the car hit the tree. I was.

8. It was snowing when they arrived in New York.