1)how many exercises you (do) since you started your homework?
2)Mrs Izard (write) this book since her husband died.
3)You (know) this man?How long you (know) him?
4)we already (tank) about it for a week.It's time to do something !
5)They (talk)for two hours and (not finish) yet.
6)Mr Dix is busy.How long he (be) busy?
7)Caroline (think) about Mark since he left.
8)How long you(have) this hat? I (have) it for years.