ANSWER

1. The children were playing outside.

2. The dog was barking at us.

3. My teacher was explaining the exercise to me.

4. I was listening to my mp3 player.

5. Those people were walking towards the library. (see)

6. The cook was preparing a tasty meal.

7. I was trying to fix my computer.

8. My friend and I were playing basketball.

9. The police were chasing the thief.

10. My sister and my brother were singing.