Complete the sentences with the past perfect form of the verbs in brackets.
1. They _____ (never / play) football until last week.
2. _____ (you / buy) a ticket before you arrived at the station?
3. I was sad because she _____ (forget) my birthday.
4. _____ (he / leave) the house when you called?
5. The children _____ (not / do) their homework, so they were in trouble.