短語(yǔ)詞組短語(yǔ)gas pre -drainage 瓦斯抽放;預(yù)抽瓦斯progressive gas pre -drainage 遞進(jìn)預(yù)抽comprehensive gas -drainage 綜合抽采gas -drainage problem 抽采問題the effect of gas -drainage 抽采效果gas drainage pressure -equalized ventilation 均壓通風(fēng)coal -bed gas drainage 煤層氣抽放large -diameter gas drainage well 大孔徑瓦斯抽放孔 返回 gas drainage