Questions 19 to 22 are based on the conversation you have just heard.

A．All the time.
B．For most of the year.
C．In the summer months.
D．For a minimum of six months of each year.

A．He liked to drink two cups of coffee before the professor’s class.
B．One cup of coffee is enough for him to keep awake in the class.
C．The professor’s class is very interesting.
D．The professor’s class is very boring.