froth layer

例句：

1. 1. The foam layer on the surface of the milk was so thick that it could not be easily removed.
   牛奶表面的泡沫层非常厚，难以轻易去除。
2. 2.The scientist used a microscope to observe the bubble layer in the liquid.
   科学家使用显微镜观察液体中的气泡层。
3. 3. The froth layer on top of the coffee was too thin to drink.
   咖啡上面的泡沫层太薄，无法饮用。