1. Boiling is always a good way of treating water.
    烧开一直是水处理的一种好办法。

2. The kettle´s boiling!
    水开了！

3. Portable boiling elements that can boil small quantities of water are useful when the right voltage of electricity is available.
    如果有相配的电压，可以煮少量水的便携式热水装置是有用的。

4. Mary: Hurry up, John! The kettle´s boiling!
    玛丽:快, 约翰! 壶里的水开了!