Dangerous and Hazardous Factors Analysis and Safety Countermeasures in the Inclined and Bedded Gypsum Mineral Deposit Underground Mining by Pillar-and-room Method是什麼意思_Dangerous and Hazardous Factors Analysis and Safety Countermeasures in the Inclined and Bedded Gypsum Mineral Deposit Underground Mining by Pillar-and-room Method在線翻譯_英語_讀音_用法_例句