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  3. As the cost of gas and oil for home heating has gone up, many Americans have switched from these fuels to wood for heating their

As the cost of gas and oil for home heating has gone up, many Americans have switched from these fuels to wood for heating their

admin2009-02-10  86
问题      As the cost of gas and oil for home heating has gone up, many Americans have switched from these fuels to wood for heating their homes. In 1973, approximately 200,000 wood-burning stoves, intended for home use, were sold in the United States; by 1979, this figure had reached one million; and by the end of 1981, there were as many as seven million home-owned wood-burning units in operation in the U. S.
     In addition to low fuel bills, many people choose these stoves because their initial cost is very low (the prices range from $ 50 kits to $ 5,000 top-of-the-line models) , and because new technology has made wood fires more efficient, cleaner, and, therefore, safer than ever before.
     One new technological feature of this type is the catalytic(催化) combustor which adds about $100 to $ 200 to the cost of the stove, but which causes much more complete combustion(燃烧) of the wood and therefore burns up more of the pollutants left by incomplete combustion and produces more heat.
     A second cost-saving innovation is a device which agitates the wood, increasing the amount of oxygen that reaches the center of the wood pile, and leading to more efficient combustion. The real advantage of this device is that it allows the owner to make use of cheap sources of wood such as dirty wood chips ( an industrial by-product) that have almost no commercial value, cost as little as $ 20 a ton, and burn very inefficiently in furnaces without an agitator.
Which of the following statements is NOT true?
选项 A、Wood-burning stoves are safer and more efficient than they used to be.
B、No factories exist for the purpose of producing dirty wood chips.
C、Both catalytic combustors and wood agitators save money in the long run.
D、Wood-burning stoves with catalytic combustors cost between $100 and $ 200.
答案D
解析 A项文中第二段提到，正确；B项最后一段括号内注明(an industrial by-product)是副产品，没有工厂专门生产的，正确；C项可从三、四两段的描述中得知，从长远来看都是省钱的好东西，正确；而D项混淆了adds about $100 to $200与costs about $100 to $200，原句是附加了钱，而不是只值这些钱，所以不正确。
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