相关单词近义词 layer 层, vein 静脉, bed 床, level 数量, band 乐队, division 划分, branch 分部, section 部分, echelon 职权的等级, social class 社会地位, class 等级临近词stratus, stratify, stratum use, stratum age, stratum gap, stratum trap, stratum bias, stratum load, stratum level, Stratum model, stratum layer, stratum board 返回 stratums