尘粒越小，质量越轻，矿尘（）越大，吸附空气的能力也越强。
参考答案：表面积
---_____that he picked up his uncle at the airport?
A．Was it when
B．When it was
C．It was when
D．When was it
《灵枢·营卫生会》认为，下焦的生理特征为（）
A.如雾
B.如泌
C.如沤
D.如渎
E.如泄
