Seventy percent of the Earth is coverd with water and most of the water on the Earth is in the ocean. 地球表面的70%由水覆盖，地球上的大部分水在海洋里。

　　Only one percent of water on the Earth is drinking water. 地球上仅有1%的水是饮用水。

　　Why are the oceans salty? 海洋为什么是咸的呢？

　　Water flows from rivers to oceans, it picks up some salt from the rocks in the river. 水从河里流向海洋，它携带着河里岩石中的一些盐。

　　So, the salty water flows into the oceans. 因此，咸水流向海洋。

　　The water in the oceans get saltier and saltier. 长此以往，海水就变得越来越咸了。