関連ワード:  is oxygen a flammable gas    is oxygen a flammable gas by itself    oxygen is a flammable gas. true or false    is oxygen a combustible gas    is o2 a flammable gas    is oxygen a non flammable gas    is oxygen a highly flammable gas    is compressed oxygen a flammable gas    is medical oxygen a flammable gas    oxygen is a combustible gas true or false