瓦斯中毒
Wǎ sī zhòng dú
Fēn zhī shàng
Divide (divergent) upper (above) branch 分枝(上)
Fēn zhī xià
Divide (divergent) lower (below) branch (lower) 分枝(下)
Fēn zhī zhōng
Divide (divergent) branch center (middle) 分枝(中)
