naturalgas天然气naturaladj.自然的；天然的；私生的natural dielectric天然电介体natural word order自然词序natural government自然政府natural conception自然受孕natural fibre hose天然纤维水带natural endemicity自然地方性natural adsorbents天然吸附材料natural boundaries天然的边界线natural draw ratio自然拉伸比Natural grit stone天然凝灰岩