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  3. Many people consider the wider use of biofuels a promising way of reducing the amount of surplus carbon dioxide (C02) being pump

Many people consider the wider use of biofuels a promising way of reducing the amount of surplus carbon dioxide (C02) being pump

admin2013-06-10  58
问题     Many people consider the wider use of biofuels a promising way of reducing the amount of surplus carbon dioxide (C02) being pumped into the air by the world’s mechanized transport. The theory is that plants such as sugar cane, maize (corn, to Americans), oilseed rape and wheat take up C02 during their growth, so burning fuels made from them should have no net effect on the amount of that gas in the atmosphere.
    Theory, though, does not always translate into practice, and just as governments have committed themselves to the greater use of biofuels, questions are being raised about how green this form of energy really is. The latest comes from the International Council for Science (ICSU) based in Paris.
    The ICSU report concludes that, so far, the production of biofuels has aggravated rather than ameliorated global warming. In particular, it supports some controversial findings published in 2007 by Paul Crutzen of the Max Planck Institute for Chemistry in Germany. Dr. Crutzen concluded that most analyses had underestimated the importance to global warming of a gas called nitrous oxide (N20). The amount of this gas released by farming biofuel crops such as maize and rape probably negates by itself any advantage offered by reduced emissions of C02.
    Although N20 is not common in the Earth’s atmosphere, it is a more potent greenhouse gas than CO2 and it hangs around longer. The result is that, over the course of a century, its ability to warm the planet is almost 300 times that of an equivalent mass of C02.
    N2O is made by bacteria that live in soil and water and, these days, their raw material is often the nitrogen-rich fertiliser that modern farming requires. Since the 1960s the amount of fertiliser used by farmers has increased sixfold, and not all of that extra nitrogen ends up in their crops. Maize, in particular, is described by experts in the field as a "nitrogen-leaky" plant because it has shallow roots and takes up nitrogen for only a few months of the year. This would make maize (which is one of the main sources of biofuel) a particularly bad contributor to global N20 emissions.
    But it is not just biofuels that are to blame. The ICSU report suggests N20 emissions in general are probably more important than had been realised. Previous studies, including those by the International Panel on Climate Change (IPCC), a United Nations-appointed body of experts, may have miscalculated their significance — and according to Adrian Williams of Cranfield University, in Britain, even the IPCC’s approach suggests that the global-warming potential of most of Britain’s annual crops is dominated by N20 emissions.
It can be inferred from the third paragraph that
选项 A、biofuels have played a positive role in fighting the global warming.
B、N20 may have a greater use in fighting the global warming.
C、the ICSU report contains different findings about C02 from that of Dr. Crutzen’s.
D、Dr. Crutzen’s findings in 2007 has not been largely recognized by the world.
答案D
解析 推理判断题。第三段第二句谈到，ICSU的报告支持Dr．Crutzen的研究结果，其中findings前用到了controversial(有争议的)一词，说明当时很多人并不赞同Dr．Crutzen的研究结果，故[D]正确，同时由该句中的supports排除[C]。[A]中的positive与第三段首句相矛盾，故排除；Dr．Crutzen认为人们低估了N2O在全球变暖中的作用，这里的“作用”当然指的是消极的，而不是说N2O能用于fighting the global warming，故[B]理解错误。
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