单项选择题
A. did B. didn't C. does D. doesn't
A．吸烟危害健康、污染空气。 B．空气污染及吸烟危害了人的健康。 C．吸烟不仅对健康有害，而且增加空气污染程度。 D．吸烟增加空气污染的程度与吸烟危害人体健康的程度一样大。
A. in a dentist’s office. B. In a drug store. C. In a hospital. D. In a doctor’s office.