与动脉粥样硬化、心肌梗死、心绞痛密切相关的室内空气污染物是（）。
A.CO2
B.甲醛
C.氡
D.挥发性有机物
E.病原微生物
参考答案：A
—Oh, Mrs. King, your necklace looks nice. Is it new?
—No, I _____ it for two years. [ ]
A. had
B. have had
C. bought
D. have bought
古人评论隋朝大运河说：“天下转漕，仰此一渠。”指的是隋朝大运河的主要功能为
A．灌溉
B．泄洪
C．运输
D．饮水
