sentences: metal is a thermal / thermal energy conductor & a spoon sometimes is made of metal ->  a metal spoon is a thermal conductor  tea is a kind of substance & a hot substance is a source of heat ->  hot tea is a source of heat  hot tea is a source of heat & a metal spoon is placed in a cup of hot tea ->  the hot tea is a source of heat for the metal spoon  a metal spoon is a thermal conductor & the hot tea is a source of heat for the metal spoon & if a thermal conductor is exposed to a source of heat, then thermal conduction will make the thermal conductor become hot -> the metal spoon will be heated up by thermal conduction