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  3. We all know (or should know) by now that the carbon dioxide we produce when we burn fossil fuels and cut down forests is the pla

We all know (or should know) by now that the carbon dioxide we produce when we burn fossil fuels and cut down forests is the pla

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问题    We all know (or should know) by now that the carbon dioxide we produce when we burn fossil fuels and cut down forests is the planet’s single largest contributor to global warming. It persists in the atmosphere for centuries. Reducing these emissions by as much as half by 2050 is essential to avoid disastrous consequences by the end of this century, and we must begin immediately.
   But this is a herculean undertaking, both technically and politically. There is, however, a short-term strategy. We can slow this warming quickly by cutting emissions of four other climate pollutants: black carbon, a component of soot; methane, the main component of natural gas; lower-level ozone, a main ingredient of urban smog; and hydrofluorocarbons, or HFCs, which are used as coolants. They account for as much as 40 percent of current warming.
   We can reduce black carbon emissions significantly in the next few decades by using particulate filters on cars and trucks and switching to low-sulfur diesel. By employing those strategies, California, for instance, has cut the warming effect from diesel emissions by nearly half since the late 1980s. In addition, we can further reduce emissions of black carbon and carbon monoxide (which produces lower-level ozone) in the developing world simply by turning to efficient biomass cook stoves instead of using traditional mud stoves, by replacing kerosene lamps in villages with solar lamps, and by deploying modern brick kilns.
   Methane emissions can be cut by nearly a third by reducing leaks from gas pipes, coal mines and hydraulic fracturing, by capturing methane from waste dumps, water treatment plants and manure, and by cutting emissions from rice paddies.
   These reductions in methane, carbon monoxide and volatile organic compounds would also significantly reduce lower-level ozone, which is another important climate-warming pollutant that is formed by the interaction of sunlight with other short-lived pollutants.
   And HFCs, which are widely used in refrigerators, can be replaced with readily available climate-friendly refrigerants. Nearly 100 ozone-depleting chemicals have been phased out under the Montreal Protocol, an international treaty that took effect in 1989 , and more than 100 countries support a shift to the safer HFC alternatives. Phasing down HFCs would provide climate protection many times greater than the current Kyoto climate treaty—the equivalent of about 100 billion tons of carbon dioxide by 2050.
   Unlike carbon dioxide, these pollutants are short-lived in the atmosphere. If we stop emitting them, they will disappear in a matter of weeks to a few decades. These reductions would also prevent an estimated two to four million deaths from air pollution and avoid billions of dollars of crop loss annually, according to a study commissioned by the United Nations Environment Program and the World Meteorological Organization.
The word "herculean"(Line 1, Paragraph 2) is closest in meaning to______.
选项 A、powerful
B、easy
C、glorious
D、difficult
答案D
解析 此题为词义理解题。此类题要结合具体语境，联系上下文进行分析。该句话的意思是，但是，不管从技术层面还是政治层面上讲，这都是一项……的任务。接着下句发生转折，不过，这里还有一项短期策略：可以通过减少碳黑、甲醇、低层臭氧和氢氟碳化合物四种污染物来迅速的减缓气候变暖。结合四个选项，显然D选项为正确答案。
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