関連ワード:  is gas flammable or combustible    is gasoline flammable or combustible    is cs gas flammable or combustible    is natural gas flammable or combustible    is sewer gas flammable or combustible    is oxygen gas flammable or combustible    is hydrogen gas flammable or combustible    is methane gas flammable or combustible    is gasoline a flammable or combustible liquid    is gas flammable