Passage Three Questions 22 to 25 are based on the passage you have just heard.

A．To promote gender equality and childhood development.
B．To fill a gap in China’s museum construction history.
C．To promote the growth of economy.
D．To boost the development of Beijing’s Chang’an Avenue.

A．The purpose of laughter.
B．The cause of laughter and its effects.
C．Why and when people laugh.
D．The origin of laughter.