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  3. Planes may account for only 2 per cent of the world’s carbon emissions, but it is a figure destined to rise. The aviation indust

Planes may account for only 2 per cent of the world’s carbon emissions, but it is a figure destined to rise. The aviation indust

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问题     Planes may account for only 2 per cent of the world’s carbon emissions, but it is a figure destined to rise. The aviation industry is expanding at a dramatic rate, around 5% a year. Twice as many passengers are likely to be passing through British airports in 2020 compared with today, and three times by 2030.
    As the developed world acknowledges climate change warnings, the carbon emissions from other industries will fall. The aviation industry’s output will therefore account for an even larger percentage of emissions. One calculation, by the Climate Change Research(CCR), suggests the U. K. aviation industry could end up accounting for every gram of our carbon quota by 2040. Such calculations suppose aircraft designers cannot clean up their act, a suggestion firmly rejected by experts who point to a massive research program aimed at cutting fuel use by planes by around 50% by 2020, a move that would also halve their carbon emissions.
    To reach that aim, a key factor will be lightweight composites, materials made of several components, including carbon fibers. These are as strong and flexible as metal but as light as plastic. Planes such as the Airbus A340 are already made of material that is 10 per cent carbon composite. This cuts weight, decreases fuel use and reduces carbon emissions. The next generation of aircrafts, will make even more use of composites: a tremendous saving in weight, fuel and carbon.
    Then there is the simple matter of air traffic control. At present, individual countries have their own routes for aircraft crossing their airspaces. "Essentially aircraft travel on doglegs across Europe, and that is very inefficient in terms of fuel use," said Dr. John Green, of the Royal Aeronautical Society. "We need to rationalize air traffic control so that planes fly in straight, energy-efficient lines, an idea that is now being discussed in the EU. "
    Finally, there is aviation fuel. Making it ecologically friendly poses the greatest challenges of all. Biofuels can be used as petrol and diesel substitutes for cars and lorries, but not in planes. "Biofuel is essentially alcohol, and that burns at the wrong temperature for aircraft engines," says Green. "We can use coal to make kerosene, which we could burn in aircraft engines, but that does not help the issue of global warming, of course. " But this does not stop scientists from dreaming. One idea, put forward by the U. S. geneticist Craig Venter last week, would be to create micro-organisms, fitted with artificial chromosomes, which could convert sunlight into fuels that could be burnt in aircraft. These would not involve burning fossil carbon and would be the perfect green fuel. It is still a far-off prospect but realistic, say biologists.
In order to reduce carbon emissions, airlines can
选项 A、change air traffic routes to make it straight and shorter for a flight.
B、use lighter materials like composites in building a plane.
C、reduce the number of engines on a plane to cut weight.
D、produce environment-friendly fuels.
答案A
解析 为了减少碳排放量，航空公司可以[A]改变航线，采用直线型的、更短的航线。[B]在制造飞机时使用合成材料这类更轻的材料。[C]减少飞机引擎的数量以减轻飞机重量。[D]生产环保型的燃料。题干内容是关于航空公司可以采取的减少碳排放量的措施。从第三、四、五段的第一句话分别可以得知[A]、[B]和[D]为对应的可以采取的措施，但是落实到航空公司来说，只有[A]可行。[B]和[D]分别为飞机制造业和能源业的努力方向。[C]提到了减少引擎数量从而减少飞机重量，这在文中没有提及。所以[A]为答案。
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