A、Half an hour. B、Longer than half an hour. C、Longer than an hour. D、It depends on different people. A

W: Can you recommend some universities with good graduate schools?
M: Well, generally in the US each university has its own special fields in which it is particularly outstanding. A large university is not necessarily good in every field.
Q: What does the man mean?

W: Can you tell me how long a formal visit lasts in the U.S.A?
M: It depends. Usually half an hour. It can last a bit longer if tea or coffee is brought, but never longer than an hour. Remember in no circumstances should you get your host tired of seeing you again.
Q: In most circumstances, how long does a visit last?