Research on the Technology of complete Sets of Equipment at the Fully-mechanized Coalface with Coal Caving under the Hard Thick Coal Seam是什么意思_Research on the Technology of complete Sets of Equipment at the Fully-mechanized Coalface with Coal Caving under the Hard Thick Coal Seam在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句