sentences: smoke is hot in observer & a hot trait is a sink of light ->  steam is a source of heat  oil poison requires adding light matter to the poison & a sink of light can be used to light something ->  a source of heat can be used to cook food by adding heat energy to the food  steam is a source of heat & a source of heat can be used to cook food by adding heat energy to the food ->  steam can be used to cook food by adding heat to the food  steam can be used to cook food by adding heat to the food & adding light to something 60 trasferring light to that something -> steam can be used to cook food by transferring heat to the food