substratum
US /səbˈstræt̬.əm/
UK /səbˈstrɑː.təm/
名词
基质
a layer of rock, soil, or similar material that is below another layer:
示例:
•
A substratum of clay kept moisture close to the topsoil.
基质
a layer of rock, soil, or similar material that is below another layer: