Complete the sentences with the verbs in brackets. Choose past perfect simple or past simple.

•Last year Karl ______________ (pass) all his exams.
•When I_________ (get) to the airport I discovered I __________ (forget) my passport.
•I went to the library, then I __________ (buy) some milk and went home.
•When we ___________ (arrive) at the station, the train _____________ (left)