natural son私生子naturaladj.自然的；天然的；私生的natural ground-water level天然地下水位natural electromagnetic wave天然电磁波natural precipitation method自然沉降法natural protection programme天保工程natural conservation culture生态文明natural gas release from oil油溶天然气出溶natural resource development自然资源开发natural resources of tourism自然旅游资源natural resources protection自然资源保护natural language recognition自然语言识别