Plants are chemical factories. Many of the chemicals that they produce are useful to humans. Besides food, plants provide material for paper, buildings, medicines and many others. Scientists study the chemicals to treat certain types of cancer.

On the other hand, the fast growth of the human population is changing the earth quickly. Only by understanding how human activities affect our environment can we predict global climate changes. Scientific studies of these changes and their effect on natural ecosystems and crop production are of great importance to the future of our society.

Other environmental issues, such as pollution, also interest scientists. Many plant species are especially sensitive to certain pollutants. Scientists study the effects of different types of pollution on plants. They use their results to advise lawmakers to make laws for environmental protection and to save priceless natural areas.

By using plant tissue culture（植物细胞培养），scientists can grow plants from single cells. This has exciting possibilities in biotechnology, forestry and so on. For example, the American chestnut was once a widespread tree in the Eastern forests. Today it has nearly disappeared because of a disease-producing fungus that causes chestnut to die. The American chestnut recently has been grown in plant tissue culture.

The earth’s biological diversity or the kinds of living things are decreasing. As humans change the environment for their own purposes, plants and animals living in these areas become increasingly endangered．Scientists work to identify and understand new plant species, especially in such biologically rich areas as rain forests. Perhaps a plant undiscovered now will become an important food crop. There are probably many undiscovered plants that produce useful drugs to cure or treat human disease. Biological diversity also provides an important source of new genes to improve the plants we now use. As techniques of genetic engineering improve, so will our ability to improve our plants.

1．Which of the following is not true according to this passage?

A．All the chemicals we need are produced by plants.

B．If we can understand how human activities affect our environment, we can predict global climate changes.

C．Science plays an important role in improving the plants.

D．Scientists use their scientific study results to make laws for environmental protection and to save priceless natural areas.

2．We can know from the Paragraph2 and Paragraph3 that_______.

A．it is global climate changes that endanger plant

B．human activities influence plants greatly

C．pollution does little harm to many plants

D．scientific studies on plant species are important to stop pollution

3．The underlined sentence means___________.

A．plants can produce many chemicals needed in chemical factory

B．plants can be made into many products in factories

C．scientists can use plants to study many chemicals

D．scientists can offer people many necessary materials

4．The importance of biological diversity lies in that_____________________.

A．we can have new species to take the place of the endangered

B．it can populate the earth with as many plants as possible

C．it has many possible values to human being

D．people may use it to cure or treat human disease

5．The best title for the passage might be ____________.

A．Finding New Plant Species

B．Botany and Society

C．The Chemical Factories

D．New Genes to Improve the Plants

The Greenbelt, a wide belt of open land around the cities and towns of the San Francisco Bay Area, includes about 3.75 million of the Bay Area’s 4.5 million acres. The Bay Area Greenbelt is one of the largest areas of open land in any U.S. urban area. Open land is land that has few buildings and lots of natural areas. The Greenbelt’s open land includes parks, forests, beaches, and more than 8,500 farms.
What are the advantages of the Greenbelt?
The Greenbelt has many advantages for people in the Bay Area, which include:
l walking and biking areas close to the cities and towns;
l places for wild plants and animals;
l cleaner air and water;
l income from farms.
Is the Greenbelt in danger?
Five hundred seventy thousand acres of the Greenbelt are in danger. There are builders who want to build suburbs on them. If those acres become suburbs, many things will change:
l the urban and suburban area will almost double;
l many farms will disappear;
l traffic will become worse; 
l the air will become dirtier.
What is Greenbelt Alliance (联盟)?
Greenbelt Alliance, an organization that saves land in the San Francisco Bay Area, works alone and with other groups to save the Greenbelt in four ways:
1. Try to persuade people to build new buildings on land that is already urban, not on open land.
2. Make sure that the city and town governments are all making plans to save the Greenbelt.
3. Help Bay Area towns and cities to buy pieces of open land to make into natural areas.
4. Teach people in the Bay Area why the Greenbelt is important and what they can do to help save it.
【小题1】What can we learn about the Greenbelt from the first paragraph?

The Greenbelt, a wide belt of open land around the cities and towns of the San Francisco Bay Area, includes about 3.75 million of the Bay Area’s 4.5 million acres. The Bay Area Greenbelt is one of the largest areas of open land in any U.S. urban area. Open land is land that has few buildings and lots of natural areas. The Greenbelt’s open land includes parks, forests, beaches, and more than 8,500 farms.

What are the advantages of the Greenbelt?

The Greenbelt has many advantages for people in the Bay Area, which include:

l walking and biking areas close to the cities and towns;

l places for wild plants and animals;

l cleaner air and water;

l income from farms.

Is the Greenbelt in danger?

Five hundred seventy thousand acres of the Greenbelt are in danger. There are builders who want to build suburbs on them. If those acres become suburbs, many things will change:

l the urban and suburban area will almost double;

l many farms will disappear;

l traffic will become worse; 

l the air will become dirtier.

What is Greenbelt Alliance (联盟)?

Greenbelt Alliance, an organization that saves land in the San Francisco Bay Area, works alone and with other groups to save the Greenbelt in four ways:

1. Try to persuade people to build new buildings on land that is already urban, not on open land.

2. Make sure that the city and town governments are all making plans to save the Greenbelt.

3. Help Bay Area towns and cities to buy pieces of open land to make into natural areas.

4. Teach people in the Bay Area why the Greenbelt is important and what they can do to help save it.

1.What can we learn about the Greenbelt from the first paragraph?

A．The Greenbelt is the largest open land in the United States.

B．The Greenbelt covers much more than half of the Bay Area.

C．There are few farms on the open land of the Greenbelt.

D．There are more than 8,500 natural areas on the Greenbelt.

2.One of the advantages of the Greenbelt for people in the Bay Area is __________.

A．convenience for exercise                 B．income from sightseeing

C．cleaner city streets                      D．more plants and animals

3.The Greenbelt is in danger because __________.

A．traffic is getting worse

B．some plans to build suburbs on it

C．the suburban area has doubled

D．pollution is becoming serious

4.Which of the following is TRUE about Greenbelt Alliance?

A．It builds new buildings on open land.

B．It buys large open land for the Bay Area.

C．It educates people how to save the Greenbelt.

D．It helps the city governments make plans.

More than 200 scientists have completed a two­year study to identify the most natural and undeveloped areas on Earth. Their findings are reported in a new book called Wilderness：Earth’s Last Wild Places. The book describes 37 wilderness areas around the world. Each has an area greater than 10,000 square kilometers. The study considered only areas where at least 70% of all plants are native.

North and South America are home to the largest number of wilderness areas. There are 16 such areas, from southern Argentina to Alaska and northern Canada. Africa has 8 wilderness areas, including the thick forests and the grasslands. Australia and New Guinea (几内亚) share 6 areas. Europe has 3 areas and Asia has 2.The Arabian Desert and Antarctica also are considered wilderness areas.

The largest wilderness area is the Boreal Forest (北方森林)．It extends for 16­million square kilometers south of the Arctic Circle. The Boreal Forest extends across Alaska, Canada, northern Europe and Russia. The smallest of the 37 wilderness areas is the Sundarbans. It is the world’s largest tidal mangrove forest (红树林)．It covers 10,000 square kilometers of land at the mouth of the Ganges River in India and Bangladesh (孟加拉国)．

The study found that wilderness areas cover about 46% of the Earth’s land surface. However, they are home to less than 2.5% of the world’s population. Nineteen of the wilderness areas have only about one person for each square kilometer. Native people usually live in these areas.

Wilderness areas help to influence the world’s weather systems and rainfall. They are also home to many plants and animals. Population growth and the spread of agriculture and mining operations threaten wilderness areas. But just 7% of all such areas have some form of official protection.

1.What does the author think of the wilderness areas around the world in the book?

A．Unwanted.        B．Long-lasting.       C．Valuable          D．Perfect.

2.The writer describes the wilderness areas to show that they ________.

A．are worth the public support              B．can attract readers’ attention

C．need to be stressed as resources           D．are seen on every continent

3.According to the 4th paragraph, we can draw a conclusion that the 37 wilderness areas are ________.

A．deserted          B．crowded          C．uncontrolled       D．undeveloped

4.As the result of the effect on nature, the wilderness areas on Earth should be ________.

A．thought more of by the governments        B．explored as natural habitats very soon

C．further made full use of at present          D．discovered for their advantages of nature

5.The purpose of writing this text is to tell us ________of the wilderness areas around the world.

A．the importance     B．the situation       C．the development    D．the environment