重点词汇

overview  美     [ˈoʊvərvjuː]  概述、概览、概况

birthplace美[ˈbɜːrθpleɪs]出生的、发源地、发祥地

border美[ˈbɔːrdər]国界、边界、与.....接壤

carbon dioxide    美[ˌkɑːrbən daɪˈɑːksaɪd]    二氧化碳

creek美[kriːk]小海湾、小港湾

inland美[ˌɪnˈlænd , ˈɪnlænd]内陆的、内地的

island 美    [ˈaɪlənd] 岛、使孤立

nitrogen美[ˈnaɪtrədʒən]氮气

population美[ˌpɑːpjuˈleɪʃn]人口、人口数量、族群

report美[rɪˈpɔːrt]汇报、报告、通报、发表、报道

representative美[ˌreprɪˈzentətɪv]代表、销售代表、销售代理

security美[sɪˈkjʊrəti]保护措施、安全工作、保安部门、保证

technical美[ˈteknɪkl]技术的、技能的、专业的

frustrated美[ˈfrʌstreɪtɪd]懊恼、沮丧 、挫败、使失忆

Overview of Earth

Earth is where we all live. 

It is our home in the solar system.

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.

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.

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

The equator which divides the earth into 2 hemispheres, is about 40,000 kilometers long.

The Earth diameter is 12,756 kilometers.

Its radius is half that, or 6378 kilometers.

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

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

The rest of the Earth’s surface is land.

Just above the Earth surface is the atmosphere.

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

These gases include oxygen,nitrogen and carbon dioxide.

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.

Water on Earth

Most of the earth’s water is in the ocean.

The two largest oceans are the Pacific (太平洋）and Atlantic Oceans（大西洋）.

Unfortunately, we can’t drink ocean water.

This is because the 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.

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.

Some rivers become very large and long.

The longest river in the world is the Nile River in Africa.

It’s almost 6,500 kilometers long.

As for the water volume, the Amazon is the largest river.

The volume of water flowing through it persecond（每秒）is more than in any other river.

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 toinland cities or lakes.