Questions 19 to 21 are based on the conversation you have just heard.

A．Stop thinking about the matter.
B．Talk the drug user out of the habit.
C．Be more friendly to his schoolmate.
D．Keep his distance from drug addicts.

A．What chemicals tears are composed of.
B．Whether crying really helps us feel better.
C．Why some people tend to cry more often than others.
D．How tears help people cope with emotional problems.