Stop and listen! What do you hear? You may hear many different sounds. Some of those sounds may be
noise. Noise is a loud or unwanted sound.
     Noise can be caused by many kinds of machines, such as motorcycles, jet planes (喷气式飞机), farm
tractors, and power motors. And, to some people, rock music is also a noise.
     What happens to people who live near noisy machines or use them over a period of time? Doctors have
found that these people have trouble in sleeping. And most importantly, constant (连续的) loud noise can cause
loss of hearing.
     Scientists use a unit of measure called a decibel (分贝) to measure the loudness of a sound. The sound of a
quiet room, for example, measures 35 decibels. Talking measures between 40 and 65 decibels. Sounds from
traffic and from some rock bands measure over 120 decibels. Noise at such high level causes the greatest
hearing loss.
(     ) 1. According to the passage, noise is all sounds that you can hear.
(     ) 2. A "decibel" is a machine that makes loud noise.
(     ) 3. Loud noise can help people sleep better.
(     ) 4. Not all people think that rock music is a noise.
(     ) 5. We can infer (推断) from the passage that noise is a serious problem.

     The students were having their chemistry class. Miss Li was telling the children what water was like. After
that, she asked her students, "What is water?" No one answered for a few minutes. Miss Li asked again, "Why
don't you answer my question? Didn't I tell you what water is like?" 
     Just then, a boy put up his hand and said, "Miss Li, you told us that water has no color and no smell. But
where to find such kind of water? The water in the river behind my house is always black and it has a bad
smell." Most of the children agreed with him. 
     "I'm sorry, children," said the teacher, "our water is getting dirtier and dirtier. That's a serious problem."
1. Why didn't the children answer the teacher's question at first?
   ________________________________________________
2. Please use a sentence to describe what water is.
   ________________________________________________
3. Why does the water in the river have color and smell?
   ________________________________________________
4. Do you think the boy who answered the teacher's question is stupid?
   ________________________________________________
5. What did other students think of the boy?
   ________________________________________________

    Plants and animals, including humans, need food and water to live on. These are from the natural resources
(资源) on Earth. To protect these resources, we need to keep the air clean and the water drinkable. We need
to keep the soil healthy. How do we do that?
* Protect the land
    The soil that covers fields and farms provides much of the food we eat. Human activities such as plowing (耕) fields, mining (采矿), and building highways can destroy (破坏) the land. Erosion happen when wind and
water carry away the soil. Soil erosion can turn rich farmland into a desert wasteland. So does this mean we
shouldn't build a highway or plow a field? Of course not. But it does mean we might think about Earth-friendly
ways of doing those things.
    Today farmers plow their fields in different ways to prevent erosion. They try to use less water for their
crops. They keep animals from eating the growing grass in just one area. Farmers also plant trees to prevent
erosion from happening.
* Save the Trees
    Another human activity that damages the land is deforestation (采伐森林). People take away a large number
of trees from a forest. Millions of square kilometers of forest disappear each year. When this happens, many
plants and animals lose their places to live. They may die out, or become very few. Scientists haven't even
discovered all the living things in the forest. We may be losing some without even knowing they are there.
Trees absorb (吸收) and use carbon dioxide (二氧化碳) when they make food. Environmentalists encourage
careful management of the forests. They ask people to replant trees after they cut down the forest. 
* Recycle, Reuse, Reduce
     People throw a piece of paper into the wastebasket after using it. The paper becomes trash. Where does
the trash go next? Much of our trash ends up in landfills (垃圾填埋地). They take up valuable land and
sometimes pollute the water, air, and land around them. More than a third of the trash in landfills is paper.
Recycling, reusing, and reducing what you throw away can cut down on the need for more landfills. In fact,
we can recycle about eighty percent of household trash.

1. What does the underlined word "erosion" mean?

A. Plowing fields and mining.
B. Cutting down trees and farming.
C. Wind and rain carrying away soil.
D. Building highways on the farmland.

2. How do farmers prevent erosion now?

A. They try to use more water for their crops.
B. They stop animals from eating the growing grass in just one area.
C. Farmers also plant flowers to prevent erosion from happening.
D. They move to another place.

3. Why do we need to save the trees?

A. To discover more new trees every year.
B. To make more money.
C. To take away a large number of trees from the forest.
D. To keep good places for animals and plants to live in.

4. How much of the trash can we recycle?

A. All the trash.
B. Very little.
C. One third.
D. Four fifths.

5. What's the purpose of the author writing the passage?

A. To ask people to look for places to plant trees.
B. To tell people how to protect natural resources.
C. To show how the lands are destroyed by people.
D. To discuss ways of protecting animals and plants.

    In the past, the people in Zhanjiang lived a poor life. The houses were old and small. 1______ (pollute) was
very serious, and there was rubbish everywhere. The traffic was not convenient, so few visitors came here.
    Now great changes have 2______ (take) place in Zhanjiang. The environment has become more beautiful.
The rivers have turned 3______ (clear) and the sky has turned bluer. There are trees, flowers and grass
everywhere. People live a better 4______. There are many large and bright buildings. Many people have their
own cars. Every year, thousands 5______ people from all over the country come to our city.
    We're sure Zhanjiang will become better and better in the future.