1) When I arrived the teacher was writing the summary.

2) He was crossing the road when I saw him.

3) Why were they shouting at you when I woke up?

4) They were fixing the computer when I opened the door.

5) Did Mary break her leg while she was skating?

6) I was sleeping when she knocked on the door.

7) When I saw Jim at the disco he wasn't talking to the Dj.

8) I was watching a film on TV when the electricity went out.

9) The Titanic wasn't crossing the Pacific Ocean when it struck an iceberg.

10) Paul didn't fall when he was running away.

11) Carol fell asleep while she was reading the book.

12) While my father was driving home, he didn't answer his mobile phone.