单项选择题
The force acting on a single cargo runner which is vertically lifting or lowering a load is greatest when（）.
A.decelerating when lowering the load B.decelerating when raising the load C.lowering the load at constant speed D.raising the load at constant speed
单项选择题 The Chief Tally would like to inquire（）the rotation of the discharging ports.
单项选择题 The cargo，when（），should be completely covered with plastic.
单项选择题 The cargo is liable to burn.Please keep it（）the engine room.
