净化厂应在（）个地方设防火防爆区域。
A.六
B.八
C.十
D.十二
参考答案：B
负荷曲线有什么用途？
--- Are you in a hurry?
--- No, in fact, I’ve got plenty of time. I _______ wait.
A．can
B．may
C．must
D．Should
