利用矿井主要通风机的压风对掘进工作面通风的通风方式称为（）通风。
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形状公差的项目有直线度、平面度、（）、圆柱度、线轮廓度、面轮廓度。
A. 圆度
B. 同轴度
C. 平行度
D. 位置度
A cabinet or space containing the controls or valves for the fixed firefighting system must be（）.
A. posted with instructions on the operation of the system
B. ventilated and equipped with explosion-proof switches
C. painted with red and black diagonal stripes
D. equipped with a battery powered source of emergency lighting
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