Practices on the top coal controlling in the fully mechanized longwall sub-level caving face under the conditions of large-area end-face roof fall是什么意思_Practices on the top coal controlling in the fully mechanized longwall sub-level caving face under the conditions of large-area end-face roof fall在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句