懂你英语文本笔记Level 3 unit2 part4 listening

Level 3 unit2 part4 listening

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 places. It’s special because of 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 other 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 the large rotating sphere about 4.5 billion years old.the equator which divide the earth into two hemespheres is about 40000 KM long. The earth deanmeter is 12756KM,its radius is half that or 6378KM.the radius is the distance from the Earth’s center to its surface.

Most of the earth’ surface is covered by water. The rest of the earth’s surface is land. Just above the earth’s surface is the atmosphere.the atmosphere is lare of gases about 500KM thick. This gases include oxygen and carben dioxide .this mixture of gases is the air that we breathe.

As we move about the earth’s surface the air gets thinner. At high altitudes the air is too thin to breathe. At the edge of the atomosphere is space. 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 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.Its almost 6500KM 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.another use of rivers is for energy .the energy of falling water is used to produce electricity.

The 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.