Mountains are landforms higher than 2000 feet,or about 600 meters,above sea level.
山脉的地形高于海拔2000英尺或约600米。
Hills are like mountains,but not as tall.
山丘就像山脉，但不像高山。
Mountains are formed by forces deep within the Earth and are made of many types of rocks.
山脉是由地球深处的力量形成的，由许多类型的岩石组成。
Rivers are streams of water that usually begin in mountains and flow into the sea.
河流是水流，通常从山上开始流入大海
Many early cities were built alongside rivers.
许多早期城市都是沿河而建的。
Most of the world's water is in the oceans, which are large bodies of salt water.
世界上大部分的水都在海洋中，这些海水是大量的咸水。
Ther oceans are also an important source of oxygen.
海洋也是重要的氧气来源。
Deserts are areas of land that receive little or no rainfall.
沙漠是几乎没有降雨的土地。
The amount of rainfall in some deserts is so low that only a few plants can survive.
一些沙漠的降雨量很低，只有少数植物可以存活.
Desert temperatures can range from cold at night to very hot during the daytime,ofern above 120 degress F.
沙漠温度可以从夜间的寒冷到白天的非常炎热，在120度以上。
A valley is a low,relatively area between hills or mountains ,often with a river running through it.
山谷是丘陵或山脉之间相对较低的区域，通常有一条河流贯穿其中.
Some valleys are formed by flowing water, and others are formed by glaciers.
一些山谷由流动的水形成，而另一些山谷则由冰川形成。
The place where a river beging is its source.
河流蜿蜒的地方就是它的来源。
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