Put the verbs in brackets into the past simple, past continuous, past perfect or past perfect continuous:
1)san (read) a book when i went to his office, so i interrupted him.
2)we didn't talk to bill at school, because when we got there he (already/go) home.
3)john (try) to fix his computer for two hours before he decided to call a professional.
4)ann (not/win) the young inventor of the year award last year, but she's sure she will this year.