Объяснение:

1 came/had already cooked

2 had studied/entered

3 saw/hadn't washed

4 had finished/came

5 had happened/rang

Ответ:

1. When i came home, my mother had already cooked dinner.

2. He had studied English before he entered the university.

3. Mother saw that Nick hadn't washed his hands.

4. I had finished me work when my son came into the room.

5. What had happened before the phone rang?

Объяснение:

правила грамматики