Division of Danger Zone and Safety Zone in No.9 Coal Bed on Mining Under Safe Water Pressure of Aquifer in Xiyu Coal Mine of Taiyuan City是什么意思_Division of Danger Zone and Safety Zone in No.9 Coal Bed on Mining Under Safe Water Pressure of Aquifer in Xiyu Coal Mine of Taiyuan City在线翻译_英语_读音_用法_例句