past simple, present perfect or present perfect continuous. 
1) You (work) in the garden for three hours already. Go home and do your homework.
2) Nick is tired because he (watch) videos since two o`clock and he (see) two films.
3)Their parents (know) jack for fifteen years.
4)We (repair) our flat for half a month.
5) She (not change) her clothes yesterday evening.
6)Where you (meet) Mary and John the day before yesterday? Помогите, плизз......