natural bar天然浅滩naturaladj.自然的；天然的；私生的natural ageing cycle自然时效周期natural system model自然体系模型natural homomorphism自然同态Natural Bamboo Fibre竹原纤维Natural Carnauba wax天然巴西棕榈蜡natural immunization自然免疫(作用)natural spider silks天然蜘蛛丝natural surveillance自然监视natural energy cycle自然能量循环natural half-width自然半宽