The writer's first marriage was unsuccessful because ______.

A．He feels sorry for those students.
B．He considers the punishment excessive.
C．He thinks it good to punish the students.
D．He disapproves of what the professor did.

A．Musical instruments developed through the years will sooner or later be replaced by computers.
B．Music cannot be passed on to future generations unless it is recorded.
C．Folk songs cannot be spread far unless they are printed on music sheets.
D．The development of music culture is highly dependent on its material aspect.