单项选择题
Questions 29 to 31 are based on the passage you have just heard.
A. Latin America. B. North America. C. South America. D. Central America.
A. Coastal isolation. B. Resistant bark and damp climate. C. Absence of natural enemies. D. Cool weather and daily fog.
A. Doctor and patient. B. Daughter and mother. C. Passenger and bus driver. D. Customer and merchant.