Ответ:
a) When we came back home, the children had already been sleeping for two hours.
b) Tina had just got home when I phoned her.
c) The film had already begun when we came to the cinema.
d) We were very tired at the end of the trip. We had been driving for ten hours.
e) I didn’t see Jim yesterday. He had gone abroad.
f) I had joined the golf club before Martin did it.