216 Oleic acid(油酸),18:1(Δ”),is the most common monounsaturated fatty acid in mammals 2.1.7 Linoleic acid, 18: 2(4, 12), and linolenic acid (亚麻酸),18:3(△9121),can not be synthesized by mammals and are called essential fatty acids(like vitamins, they have to be taken from food)2.1.6 Oleic acid（油酸）, 18:1(9 ), is the most common monounsaturated fatty acid in mammals. 2.1.7 Linoleic acid, 18:2(9,12), and linolenic acid（亚麻酸）, 18:3(9,12,15), can not be synthesized by mammals and are called essential fatty acids (like vitamins, they have to be taken from food)