血源性肺脓肿好发部位是（）。
A.右上叶后段
B.右下或左下叶基底段
C.左下叶背段
D.多发性
E.右下叶背段
参考答案：D
The boy __________ his friends was playing in the street when the earthquake happened.[ ]
A. with
B. and
C. as well
D. as far as
锅炉点火前，除尘器可以不投入使用。
