听力原文：Can the boy swim？
（14)
A．No, he can't.
B．Yes, he can't.
C．No, he can.

What can be inferred about a lake with brown water？
A．The lake is not safe for swimming.
B．The lake has a sandy bottom.
C．The water contains suspended particles.
D．The water is very deep in the center of the lake.

According to the professor, how did children acquire their culture throughout most of history？
A．By experiencing life in another country
B．By watching cultural programs on television
C．By going to the museum and the library
D．By listening to parents and grandparents

What does the student imply about golf？.
A．Golf is his favorite leisure activity.
B．He enjoys playing golf with his boss.
C．He would like to know more about golf.
D．He has never played golf before.

According to the conversation, what factors influence the color of water？ Click on two answers.
A．Waves on the surface
B．The depth of the water
C．Sediments in the water
D．The water temperature

Listen again to part of the lecture. Then answer the question. Why does the professor say this:
A．To stress the mysterious nature of severe immune responses
B．To argue that anaphylaxis is mainly the result of bad luck
C．To point out that scientists disagree over what causes allergies
D．To suggest that people are crazy to eat offending substances