A．The man must be an excellent student.
B．The man’s idea is probably a good one.
C．The man had better drop more than one course.
D．The man would not have dropped the best course of the four.

A．The boy’s hands are often dirty.
B．Many people in this area travel by air.
C．The boy shouldn’t shake hands with other people.
D．Flu can spread through shaking hands with other people.