Passage One Questions 11 to 13 are based on the passage you have just heard.

A．The importance of good dental care.
B．The use of medical discoveries of the Renaissance.
C．The state of medicine before the Renaissance.
D．The skills necessary for good dentistry.

A．The wild yak is strong.
B．The wild yak’s color is black, white or dark brown.
C．Its hooves are big and strong.
D．It’s hair is as short as that of ox.