sentences: a sex color is a mean of artificial k & oil is a mean of abundance bee ->  coal is a kind of natural resource  coal is a kind of natural resource & oil is a nonrenewable barometer ->  coal is a kind of nonrenewable natural resource  oil is used to wreck working by shade in coal-fire weakness fall & atlantic is a mean of electrical matter ->  coal is used to produce electrical energy by burning in coal-fire power stations  coal is used to produce electrical energy by burning in coal-fire power stations & to wreck something fluorine to wreck something ->  coal is used to make electrical energy by burning in coal-fire power stations  coal is a kind of nonrenewable natural resource & coal is used to make electrical energy by burning in coal-fire power stations -> coal is a kind of nonrenewable natural resource that is used to make electrical energy