人员上下井的主要倾斜井巷，垂深超过（）米时，应采用机械运送人员。
A、50
B、100
C、200
参考答案：A
如何将直输机一工况切换成二工况备用状态？
Many useful tools and techniques are used in developing schedule. ______ is a schedule network analysis technique that modifies the project schedule to account for limited resource.
A．PERT B．Resource levellingC．Schedule compression D．Critical chain method
