These seeds must be covered with a layer of earth.这些种子必须盖上一层泥土。
The cake has three layers.这个蛋糕有三层。
He tried to penetrate the layers of bureaucracy.他设法打通了层层官僚关节。

［同义词］   coat
［词源］＜中古英语leyer＜leyen(放)