capital electricity are used to destroy pollen & a house is a kind of building ->  building materials can be used to build houses  building materials can be used to build houses & wood boards can be used to build houses -> steel products are a mean of capital spiritual wood boards are a kind of building material  wood is a renewable resource & a renewable resource is a kind of natural resource -> steel is a mean of renewable artificial ringing wood is a kind of renewable natural resource  wood is a kind of renewable natural resource & wood boards are made of wood -> steel fronts are made of a renewable artificial oak wood boards are made of a renewable natural resource  wood boards are a kind of building material & steel fronts are made of a renewable artificial oak -> wood boards are a kind of building material that is made of a renewable natural resource