protective coal seam

• 保护层

protective coal seam的用法和样例：

例句

1. The glass window had a protective overcoat applied to it.
   玻璃窗涂有一层保护层。
2. All buried lines are coated with a protective covering to save them from corrosion.
   所有埋设的管道必须涂上保护层，以防生锈腐蚀。