短语词组短语coal -gas-outburst 煤与瓦斯突出Keywords Coal -gas outburst 关键字煤与瓦斯突出preventing coal -gas outburst 防治煤与瓦斯突出gas -outburst coal 瓦斯突出煤Double -outburst coal seam 双突煤层upgrade of non -outburst coal seam 非突出煤层升级 返回 coal-outburst