单项选择题
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。
单项选择题 The program we will watch is an English teaching TV program divided into 40 episodes, each of which has five acts（）
单项选择题 In my recent trip to California，virtually all leading book stores and public libraries were well-stocked with plenty of publications on China，the mysterious oriental country．（）
单项选择题 Great as Einstein was，many of his ideas have been challenged today and are being modified by the work of scientists of our time（）