Most people would describe water as a colourless liquid. They would know that in very cold conditions it becomes a solid called ice, and that when heated on a fire it becomes a vapour called steam.

• 大多数人都把水说成是一种无色液体，他们都知道，水在极冷的情况下会变成一种叫做冰的固体；而把它加热，就会变成一种叫做水蒸汽的气体。