1. Ben had been learning at the university for three years when I entered it.
2. John and Sarah had been dating for a year before they got married.
3. Freddy had been telling funny stories for half an hour when I joined the party.
4. Father had been smoking for many years before he decided to give up this bad habit.
5. Hellen had been doing her homework for two hours when her mother came from work.
6. The children had been playing in the yard for an hour and a half when mother called them in.
7. Before you came, we had been watching the film for twenty minutes.