natural VE天然维生素Enaturaladj.自然的；天然的；私生的natural seasonings天然香辛料Natural inhibitors天然抑制剂natural gas liquid天然气液natural phosphates天然磷酸酯natural skim block天然胶清胶natural vegetation自然植被natural surjection自然满射natural-gradient自然梯度natural inbreeding天然近交natural stone slab天然石板