1. A: How long have you been here?
B: I have been here for three o'clock this afternoon.
2. Yenlik and Madina haven't played tennis since last Saturday.
3. I haven't seen Joanna since she came back from London.
4. I have known Peter for three years.
5. Iskander has written three books since he moved to Paris.
6. Mary hasn't spoken to Amanda for two months.