Ответ:

1. When police arrived, we had already caught the thief.  

2. Jack had finished the test before the bell rang.

3. When Anna came to say good night, her children had already fallen.

4. Scott had already prepared dinner when her husband got home from work.

5. When Brad and Susan got married, they had known each other for 3 years.

6. She didn't enjoy the film because she had read the book before.

7. Our apartment was in a mess because I had had a birthday party the night before.  

8. We didn't go to a restaurant because we had spent all our money on clothes.  

9. Mary couldn't go skating after she had broken her leg.

10. Larry was late because he had got stuck in a traffic jam.