The mining district is generally divided into several district sublevel along the slope. Which of the following options are the sum of the slope length of the district sublevel ( )?
A、Lengthofworkingface;
B、Widthofdistrictsublevelcoalpillar;
C、Widthofupperandlowerdistrictsublevelgateways;
D、Widthofboundarycoalpillar
发布时间：2024-09-11 16:11:18
