Final Test 01(Page 182) 01 밑줄 친 them이 가리키는 것으로 가장 적절한 것은? It's almost impossible to say when humans started using them. Most likely, when people were cooking meat over a fire, they noticed that fat from the meat burned brightly. There is evidence that about 5,000 years ago people started to cook animal fat into a liquid and put the liquid into a dish with a s..