The gas grade appraising in the coal mine is a main approach to estimate whether a coal mine is a low or high gas mine,or coal &gas outburst one,and to prevent gas explosion and mine firing.是什么意思_The gas grade appraising in the coal mine is a main approach to estimate whether a coal mine is a low or high gas mine,or coal &gas outburst one,and to prevent gas explosion and mine firing.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句