Complete the sentences with either the past simple or past perfect of the verbs in brackets.
1. When I ________(come) home my mother ________(already/cook) dinner.
2. By the time she ________(get) to the cinema her boyfriend ________ (already/buy) the tickets.
3. She ________(already/ study) German before she ________(move) to Berlin.
4. When they _______(enter) the room the concert _______(already / begin)
5. My son _______(play) computer games after he ______(finish) studying.