1) Kay had felt angry because she hadn't closed the window.
2)After the police examined the flat, they had found some fingerprints.
3) The police hadn't found some fingerprints because the burglars had used gloves.
4) After the police had left, Kay hadn't cleaned her flat.
5) The police arrested the burglars two days later, after they had robbed another flat.
6) One of the burglars had explained that he had taken the hamster because he had always wanted to have a pet.
7) The burglars hadn't left some of the pizza because they hadn't already had dinner.