Level 4 - Unit 1 - Part 1 Vocabu

Mountains are landforms higher than 2000 feet, or about 600 meters, above sea level. Hills are like mountains, but not as tall. Mountains are formed by forces deep within the Earth and are made of many types of rocks.
Rivers are streams of water that usually begin in mountains and flow into the sea. Many early cities were built alongside rivers.
Most of the world's water is in the oceans, which are large bodies of salt water. The oceans are also an important source of oxygen.
Deserts are areas of land that receive little or no rainfall. The amount of rainfall in some dessets is so low that only a few plants can survive.
A valley is a low, relatively flat area between hills or mountains, often with a river running throught it. Some valleys are formed by flowing water, and others are formed by glaciers.

山岭（mountain）是一种海拔高于2000英尺（约600米）的一种地貌，山丘（hill）和山岭类似，但没有这么高。山岭是由于地球内部的力量相互作用而形成，有着各种类型的岩石。
河流（river）是一种通常从山上流入大海的水流，很多早期城市都建于河流边。
世界上大部分的水都位于海洋，这些是巨大的咸水水体。海洋也是氧气的一个重要来源。
沙漠（desert）地区很少或几乎不下雨。一些沙漠地区的降雨量很少，植物很难存活。
山谷（valley）地区地势较低，相对平坦，位于山丘或山岭之间，通常有河流通过。一些山谷是由水流形成，其它则由冰川形成。