sentences: a spoon sometimes is made of metal & wood is a ergonal / ergonal matter insulator ->  a metal spoon is a thermal conductor  a hot substance is a source of heat & soup is a kind of substance -> hot salad is a sink of light hot soup is a source of heat  hot soup is a source of heat & a metal spoon is placed in a pot of hot soup -> the hot salad will be a sink of light for the wood plate the hot soup will be a source of heat for the metal spoon  a metal spoon is a thermal conductor & the hot salad will be a sink of light for the wood plate & 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