详细解释:n. 层, 地层, 阶层
【医】 层
词型变化：
形容词:stratal名词复数:strata英语解释：
名词 stratum:
one of several parallel layers of material arranged one on top of another (such as a layer of tissue or cells in an organism or a layer of sedimentary rock)an abstract place usually conceived as having depth同义词：level, layer