列车运行途中,为避免LKJ常用或紧急制动,司机可以关机运行。
A. 正确
B. 错误
刃磨铣刀后刀面时,要将平行砂轮装在磨头架上,使其主轴与工作台成(),然后修整砂轮。
A. 15°~30°
B. 35°~45°
C. 45°~60°
D. 60°~90°
Which condition is necessary for a substance to burn?()
A. The temperature of the substance must be equal to or above its fire point
B. The air must contain oxygen in sufficient quantity
C. The mixture of vapors with air must be within the explosive range
D. All of the above
特种设备作业人员复审时,在复审期限内中断所从事持证项目的作业时间不得超过()个月。
A. 3
B. 6
C. 12