·2,447,543篇论文数据,部分数据来源于NoteExpress
N-COUNT A substratum of something is a layer that lies under the surface of another layer, or a feature that is less obvious than other features. 底层 [正式] [with supp, usu N 'of' n]
...its deep substratum of chalk.
...它的深层的白垩底土。
应用推荐