Complete using the correct form of the verbs in brackets. Use ‘could have P2’

Ex2. Complete using the correct form of the verbs in brackets. Use ‘could have P2’
0. We could have gone (go) to the party, but we decided not to in the end.
1. They __ (catch) an earlier plane, but they decided to get
the later one.
2. you (stay) longer or did you have to leave then?
3. They've left school very late, although their lessons __
(finish) early today.