esponja

例句：

1. 1. The soap bubble floated to the top of the bathtub.
   肥皂泡浮到了浴缸的顶部。
2. 2. The milk frothed up when it was added to the coffee.
   牛奶加入咖啡时起泡了。
3. 3. The foam on the surface of the milk was a sign that it had been warmed.
   牛奶表面泡沫的存在意味着它已经被加热过。