【填空题】

                             Using Garbage as a Fuel
    Garbage can be a good fuel to use. The things in garbage do not look  ______ coal, petroleum, or natural gas, ______ they are chemically similar to these fossil fuels. As we use up our fossil fuel supplies, we might be able to use garbage as ______ energy source.
    Burning garbage is not a new idea. Some cities in Europe and the United  ______ ( burn) garbage for years. The heat that is produced by burning garbage is used to boil water. The steam ______ 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 city’s garbage each year. The  amount of energy  ______  （produce） is about the same as would be produced by burning almost a half million barrels of oil!
    But there are problems in using garbage ______ a fuel. Garbage that burns ______ (easy), such as food and paper, must be separated from metals, glass, and other materials that do not burn easily. Another problem is ______ 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 me et our energy needs. This method could also reduce the amount of garbage  ______ (pile) up on the earth.