Passage Three Questions 32 to 35 are based on the passage you have just heard.

A．Because they were not easily burned and can last long.
B．Because they were very cheap materials.
C．Because they could be found here and there.
D．Because they could add artistic value to buildings.

A．The United States Copyright Office created it.
B．It does not protect artists’ techniques and procedures.
C．It has not been changed since its creation.
D．It is only applied to copies of the original work.