3.2.4 Water of Earth⭐地球上的水源

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% 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.

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Rivers are important. 

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. 

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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. 

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Another use of rivers is for energy. 

The energy of falling water is used to produce electricity. 

This use of water supplies over 20% 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.

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