1.Introduce the general idea: human body need all kinds of nourishment during the life(such as water, inorganic acid, protein, glycolipin, microbian mineral, oxygen),blood cycle for digestion.
人体在生命运动中要各种营养(水、无机盐、蛋白质、糖类脂肪、维生物矿物质,氧
),
化吸收
通过血
系统。