【单选题】

Passage Three How can we get rid of garbageDo 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 man might be able to solve both problems at the same time. (83){{U}}They suggest using garbage as an energy source, and at the same time it can save the land to hold garbage.{{/U}}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. However, garbage can be a good fuel to use. The things 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.Buring garbage is not a new ide

A、Some cities inEurope and the United States have been buring 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 Pairs, France, some power plants burn almost 2 million metric tons of the city’s garbage each year. The amount of energy produced is about the same as would be produced by buring 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 (碎屑) 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、Buring 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. What is the general tone of the passage
A、Optimistic
B．Indifferent
C．Promoting
D．Anxious