瓦斯隧道装药爆破前必须进行安全检查，确保瓦斯浓度小于1%。

Before charging and blasting in gas tunnel, safety inspection must be done to ensure the gas density less than 1%.

youdao

瓦斯隧道装药爆破前必须进行安全检查，确保瓦斯浓度小于1%。

Before charging and blasting in gas tunnel, safety inspection must be done to ensure the gas density less than 1%.

youdao