短語詞組短語impermeable material layer 不透水材料層impermeable barrier layer 非滲透性隔層bottom impermeable layer 下封閉層water -impermeable layer 不透水層relative impermeable layer 相對隔水層clay impermeable layer 黏土防滲層HDPE membrane impermeable layer HDPE 膜防滲層bottom m impermeable layer 下封閉層impermeable layer on pond bottom 池底防滲層 返回 impermeable layer