Bopp

例句：

1. 1. The milk has turned into a thick and foamy layer.
   牛奶变成了厚厚的泡沫层。
2. 2. The bubbles on the surface of the water are due to the air trapped inside.
   水面上的气泡是由于水里的空气被困住形成的。
3. 3. The bubbles burst as they reach the surface.
   气泡在到达表面时爆裂。