What are the speakers talking about?

W：The general contractor called to see if he can visit the building tomorrow morning at 9:00.
M：Does he need to see both the inside and the outside? I can be there to let him ,but I can’t stay for more than half an hour; I’ve got to attend another meeting at 10:00.
W：I think he just wants to verify some of the exterior locations for the restoration work. You probably won’t need to stay for long.
M：OK, nine o’clock is fine, then. But please make sure he knows that I only have about thirty minutes.
Number 59.What are the speakers talking about?
Number 60.Which time is suitable for the visitor and the man?
Number 61.What is the man worried about?