skim

/skɪm/

a thin layer covering the surface of a liquid

中文释义：表层；浮膜

A skim of oil formed on the surface of the soup as it cooled.

汤冷却后，表面形成了一层浮油。

The pond was covered with a green skim of algae.

池塘表面覆盖着一层绿色的藻类浮膜。