英文關鍵字
chemicals
chemistry
czech
drain
europe
european
factories
foam
frozen
ice
industrial
industry
morava
partly
plants
pollution
republic
river
rivers
stream
substances
union
waste
water
winter
英文關鍵字
chemicals
chemistry
czech
drain
europe
european
factories
foam
frozen
ice
industrial
industry
morava
partly
plants
pollution
republic
river
rivers
stream
substances
union
waste
water
winter