Answer:
1. I was making my dinner at 8 o'clock last night.
2. Joe and Sam were using the wrong program in IT yesterday.
3. Who was that guy you were dancing with at the party?
4. Paula was coming home from school when she saw an accident.
5. In 1999 my father was living in Dublin. That's where he met my mother.
6. He was opening the box when he cut his finger.
7. This time last week, we were visiting my grandmother.
8. I was sitting at the back of the classroom so I couldn't see the screen.
9. Andrew was inserting a photo into his document when the teacher stopped the class.
10. I started to do my homework when my friend sent me a message.