问题补充：
How can we get rid of garbage? Do we have enough energy sources to meet our future energy needs?
These are two important questions that many people are asking today. Some people think that men might be able to solve both problems at the same time. They suggest using garbage as an energy source.
For a long time people buried garbage or dumped it on empty land. Now, empty land is scarce. But more and more garbage is produced each year. But garbage can be a good fuel to use. The things in garbage do not look like coal, petroleum, or natural gas; but they are chemically similar to these fossil fuels. As we use up our fossil-fuel supplies, we might be able to use garbage as an energy source.
Burning garbage is not a new idea. Some cities in Europe and the United States have been burning garbage for years. The heat that is produced by burning garbage is used to boil water. The steam that is produced is used to make electricity or to heat nearby buildings. In Paris, France, some power plants burn almost 2 million metric tons of the citys garbage each year. The amount of energy produced is about the same as the world produced by burning almost a half million barrels of oil!
But there are problems in using garbage as a fuel. Garbage that burns easily, such as food scraps and paper, must be separated from metals, glass, and other materials that do not burn easily. This separation process is normally costly. Another problem is that burning garbage can pollute the air.
Our fossil fuel supplies are limited. Burning garbage might be one kind of energy source that we can use to help meet our energy needs. This method could also reduce the amount of garbage piling up on the earth.
53What two problems can be solved by burning garbage?
A. The shortage of energy; Air pollution.
B. The shortage of energy; the shortage of empty land for holding garbage.
C. Air pollution; the shortage of empty land for holding garbage.
D. Air pollution; the shortage of fossil fuel.
54.Which of the following is NOT a result of burning garbage?
A. The heat produced is used to boil water.
B. The steam produced is used to make electricity.
C. The garbage burned is turned into fossil fuels.
D. The steam produced is used to heat buildings.
55.According to the passage. Which of the following four groups of garbage is ready for burning?
A. food scraps and metals B. paper and glass
C. metals and glass D. food scraps and paper
56.What is the general tone of the passage?
A. optimistic B. indifferent C. advocating D. anxious B
答案：
(答案→)B
解析：
