kier-boiling

例句：

1. 1. The water in the kettle is starting to boil.
   水壶里的水开始沸腾了。
2. 2. The soup is coming to a boil.
   汤快要沸腾了。
3. 3. The milk was overheated and started to boil.
   牛奶过热了，开始沸腾了。