Language points (15min)
1.consist of : include; be made of 由…组成
e.g. Water consists of hydrogen and oxygen.
2.divide :划分;把整体分成若干部分;
separate : 分隔;把原来连在一起或靠近的分隔开来。
e.g. The world is divided into five continents.
The grinding machine separates the grain from the husk . [hʌsk]
碾谷机把米和糠分开。
consist in = lie in 存在与;在于(无被动形式) eg: The beauty of air travel consists in its speed 。