Complete the sentences with the past simple form of the irregular verb in brackets.
1 We __________ (go) to Greece for our holidays.
2 They ___________ (leave) on the first train.
3 My friends ___________ (give) me a surprise party last weekend.
4 I ___________ (write) them an email about it.
5 I ________ (see) my old friends at the concert.
6 I __________ (know) all about it before them.