natural oil天然油naturaladj.自然的；天然的；私生的natural caving mining method自然崩落法Natural mountains and rivers自然山川natural ecological imbalance自然生态危机naturalism education thought自然主义教育思想natural resources'protectionnatural-convection cooling自然对流冷却naturalization of parameters参数归一化natural extracts of rosemary天然迷迭香natural ventilating dry kiln自然通风干燥窑Natural circulation capacity自然循环能力