overview of Earth

Earth is where we all live.  

It is our home in the solar system.

ps:它是我们在太阳系的家。

home in将注意力集中; 对…寻的，导向

solar system太阳系; 类太阳系

There is no other place for us to live.

Earth isn't just any planet.

It's a very special place.

It's special because we depend on it for many things.

Because of its importance we need to take care of it.

Exercises:

1.why is earth so special?

It's special because we depend on it for many things.

2.Because of its importance we need to take care of it.

We depend on the Earth for its air, its water and many of its natural resources. 

Natural resources, such as coal and oil, give us energy.

Other natural resources we depend on include forests and soil.

Forests provide clean air and wood for building houses.

Soil is needed to grow plants and keep them healthy.  

We need to take care of these resources and not waste them.

Exercises:

1.what are the examples of natual resources?

coal and oil

2.why do we need forests?

Forests provide clean air and wood.

3.Soil is needed to grow plants and keep them healthy.  

4.Other natural resources we depend on include forests and soil.

The Earth is a large, rotating sphere, about 4.5 billion years old. 

ps:地球是一个巨大的旋转球体，大约45亿年前。

Earth世界; 地球; 陆地; 地面; 大地; 土; 泥; 泥土; 把接地

large大的; 大规模的; 大量的; 大型号的; 广泛的; 众多的

rotating sphere旋转球

about大约; 左右; 将近; 几乎; 到处; 处处; 各处; 关于; 对于; 目的是; 为了; 涉及…方面; 忙于; 从事于; 在附近的; 四处走动的; 在起作用的; 在流行中的

billion十亿; 数以十亿计; 大量; 一万亿

years old岁; 年龄; 当我八岁时

The equator, which divides the earth into two hemispheres, is about 40,000 kilometers long.

ps:赤道把地球分成两个半球，长约4万公里。

equator赤道

which哪一个; 哪一些; …的那个，…的那些; 那个，那些

earth世界; 地球; 陆地; 地面; 大地; 土; 泥; 泥土; 把接地

into到…里面; 进入; 朝; 向; 对着; 撞上; 碰上

two二

hemispheres半球; 北半球，南半球; hemisphere的复数

kilometers千米，公里; kilometer的复数

long长的; 长; 长时间的; 长久的; 长期的; 长期地; 长久地; 很久地; 用于名词

The Earth's diameter is 12,756 kilometers.

ps:地球的直径是12756公里。

Earth世界; 地球; 陆地; 地面; 大地; 土; 泥; 泥土; 把接地

diameter直径; 对径; 放大率; 放大倍数

kilometers千米，公里; kilometer的复数

Its radius is half that, or 6,378 kilometers.

The radius is the distance from the Earth's center to its surface.

ps:半径是从地球中心到其表面的距离。

radius半径; 半径范围; 周围; 桡骨

distance距离; 间距; 遥远; 久远，间隔; 远方; 远处; 拉开距离; 与…疏远

from从…起，始于; 从…开始; 寄自，得自

Earth世界; 地球; 陆地; 地面; 大地; 土; 泥; 泥土; 把接地

center篮球中锋，中场手; 中心，中心区，中央，中枢，核心，中间派，中心站，中线; 集中，把……聚集在

surface表面; 表层; 面; 水面; 地面; 液面; 顶面，操作台; 升到水面; 浮

Most of the Earth's surface is covered by water.

The rest of the Earth's surface is land.

Exercises:

1.what divides the earth into two hemispheres?

the equator

2.what covers the  most of the earth's surface?

Most of the Earth's surface is covered by water.

3.Most of the Earth's surface is covered by water.

4.Earth is where we all live.  

5.Natural resources, such as coal and oil, give us energy.

Just above the Earth's surface is the atmosphere.

The atmosphere is a layer of gases about 500 kilometers thick.

These gases include oxygen, nitrogen and carbon dioxide.

ps:这些气体包括氧、氮和二氧化碳。

These这些，他们; 这些; 一些

include包括; 包含; 使成为…的一部分

oxygen氧; 氧气

nitrogen氮; 氮气

carbon dioxide二氧化碳

This mixture of gases is the air that we breathe.

As we move above the Earth's surface, the air gets thinner.

At high altitudes, the air is too thin to breathe.

At the edge of the atmosphere is space.

There is no air at all in space.

Exercises:

1.what is at the upper edge of the atmosphere?

space

2.above  how thick is the atmosphere?

it's about 500 kilometers thick.

3.This mixture of gases is the air that we breathe.

4.Just above the Earth's surface is the atmosphere.

5.