22.一球上大洋的含盐量

the salinity of the earth’s oceans

21.与纯水混合 mix with pure water

20.有一个相对高的结冰点

have a relatively high freezing point

19.水在室温下是液体

water is a liquid at room temperature

18.为其他生物所利用become available to

　other living creatures

17.分解固体和气体　

break down both solids and gases

16.一种极性微粒　　 a polar molecule

15.由两个氢原子和一个氧原子组成be made up if two hydrogen atoms and one oxygen atom

14.赋予水以独特的特性

give water it unique properties

13.水的化学结构 the chemical structure of water