find the mistake and correct it

[Rana H]

1) They Have Just Finished
2)I Haven't Played Tennis 4 aweek
3)He went to london in 1999
4)We Haven't Met for 5 years
5)it's a year since he phoned us
6)he has studied english for 5 years
7)he hasn't emailed us since last month
8)it's a long time since he wrote to me