renewable is the opposite of nonrenewable & something cannot have two opposite properties ->  something cannot be renewable and nonrenewable  something cannot be renewable and nonrenewable & fossil fuels are a nonrenewable resource ->  fossil fuels cannot be renewable  renewable is a property of resources & if something cannot have a certain property then something else with that property is not that something ->  if one resource cannot be renewable then another resource that is renweable is not that one resource  fossil fuels cannot be renewable & if one resource cannot be renewable then another resource that is renweable is not that one resource ->  if something is renewable then that something is not a fossil fuel  if something is renewable then that something is not a fossil fuel & wood is a renewable resource -> wood is not a fossil fuel