Reverse Direction Mining Research on the Fifth and Sixth Seam at the Ping Dingshan Fifth and Sixth Coal Mine with Stubble Repeating relationship是什么意思_Reverse Direction Mining Research on the Fifth and Sixth Seam at the Ping Dingshan Fifth and Sixth Coal Mine with Stubble Repeating relationship在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句