pillar method of stopingpillar method of workingpillar systempillarmethodofstopingpillarmethodofworkingpillarsystem式: type; style采矿: mining; mine法: law房柱式采矿法: stoop-and-room system单迸路柱式采矿法: single stall method下载手机词典可随时随地查词查翻译
