S1. What does the survey "The Mood of American Young People" try to find

A．There are too many courses offered to students.
B．The woman should take fewer courses next term.
C．The man will take four courses next semester.
D．It is wiser to take more than four courses.

A．It has been increasing since the Ice Age.
B．It affected the growth of trees.
C．It is determinated by the chemicals in the air.
D．It follows a certain cycle.