Most of the Earth's water is in the oceans.
The two largest oceans are the Pacific and Atlantic oceans.
Unfortunately, we can't drink ocean water.
This is because ocean water has too much salt.
Fortunately, there is also water in lakes and rivers.
This water isn't salty, so we can drink it.
Only about 2 percent of the world's water is fresh water.
Without fresh drinking water, we can't live.
A person can't live for more than a few days without water.
地球上大部分的水都在海洋里。两个最大的海洋是太平洋和大西洋。不幸的是，我们不能喝海水。这是因为海水含盐过多。幸运的是，在湖泊和河流里也有水。这水不咸，所以我们可以喝。世界上只有2%的水是淡水。没有新鲜的饮用水，我们不能生存。一个人几天没有水将不能够生存。
Most rivers begin in mountains and end in the oceans.
The water flows from high ground to low ground.
At first, rivers are small and are called creeks or streams.
As water enters from other streams, a river grows.
大多数河流始于山脉，止于海洋。水从高地流到低地。起初，河流很小，被称为小溪或小溪。当水从其他小溪流入时，一条河就形成了。
Some rivers become very large and long.
The longest river in the world is the Nile River in Africa.
It's almost 6500 kilometers long.
As for water volume, the Amazon is the largest river.
The Volume of water flowing through it per second is more than in any other river.
有些河流变得又大又长。世界上最长的河流是非洲的尼罗河。它几乎有6500公里长。就水量而言，亚马逊河是最大的河流。每秒流过它的水量比任何其他河流的流量都要大。
Another use of rivers is for energy.
The energy of falling water is used to produce electricity.
This use of water supplies over 20 percent of the world's electricity.
Rivers are also important for agriculture.
Without water, farmers cannot grow food.
And of course rivers can be used for transportation.
River boats are used to carry things to inland cities or lakes.
河流的另一种用途是能源。落水的能量被用来发电。这种用水供应占世界电力供应的20%以上。河流对农业也很重要。没有水，农民就不能种植粮食。当然河流也可以用来运输。内河船被用来运送货物到内陆城市或湖泊。
