Dangerous and Hazardous Factors Analysis and Safety Countermeasures in the Inclined and Bedded Gypsum Mineral Deposit Underground Mining by Pillar-and-room Method是什么意思_Dangerous and Hazardous Factors Analysis and Safety Countermeasures in the Inclined and Bedded Gypsum Mineral Deposit Underground Mining by Pillar-and-room Method在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句