题目内容：

Our factories and homes burn coal and oil. Every year we have forest fires somewhere. Many scientists believe that the weather is changing.

The earth will perhaps be warmed by about 7℃ at the South Pole(极) and the North Pole. The ice will be melt(融化). The sea level(平面) will rise by about 7 meters. As a result, water will cover cities like London, Tokyo and New York. Some ports(港口) and towns along the coasts will disappear under water.

Some other scientists think that the dust, smoke and pollution from coal, wood and oil fires will block out(封闭) the ultraviolet rays(紫外线). Then the earth will become colder and great sheets of ice will cover Europe and North America.

When chemicals in the air mix with rain, we have acid(酸) rain. Acid rain can bring us great harm. It destroys(破坏) forests and kills life in lakes and rivers.

People are beginning to see how serious the problem is. They find it important to work with nature instead of against it. They are trying to save the earth in many different ways. But one of the most important things to do is to make people understand that saving the earth is saving ourselves.

根据材料内容选择最佳答案，并将其标号填入题前括号内。

1.Some scientists believe that.

A. the earth is growing warmer

B. we have to burn down the forests every year

C. we can find oil in our forests

D. we need coal in our forests

2.Ice at the poles willif the earth gets warmer.

A. become thicker by seven meters

B. cover cities like London and Tokyo

C. raise the sea level by 7 degrees

D. become water and make the sea rise

3.Acid rain can.

A. bring great changes in our weather

B. kill pests(害虫) in lakes and forests

C. kill the fish in rivers and lakes

D. cover Europe and North America

4.What can we learn from the third paragraph?

A. The dust together with pollution from coal, wood and oil fires will bring us more heat from the sun.

B. The ultraviolet rays will come more because of the dust and pollution from fires.

C. According to the scientists, the change in weather hardly has anything to do with the pollution.

D. As a result of the dust and pollution from coal, wood and oil fires, the earth will become colder.

5.Which sentence is TRUE?

A. The weather is changing just because of the acid rain.

B. People have come to know the importance of working with nature.

C. All the scientists agree that our earth is sure to become warmer and warmer.

D. The sea level will rise if the earth gets colder.