架空明线的标准杆距是（）米。
A.20
B.30
C.40
D.50
参考答案：D
An American girl survived the plane crash that killed the rest of the passengers _____.
A．abroad
B．aboard
C．broad
D．board
除住宅外的多层民用建筑、厂房和丙类仓库的哪些部位应设置消防应急照明灯具？
