There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changin

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问题     There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO2 and further boosting global warming.
    There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase.
    Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels.
    Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO2 yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming.
We can learn from the passage that______.

选项 A、some feedback mechanisms may slow down global warming
B、the basic facts of global warming are unknown
C、developing countries benefit from cheap fossil fuels
D、developed countries have decided to reduce their energy consumption

答案A

解析 文章第一段“There are hidden factors which scientists call‘feedback mechanisms’.No one knows quite how they will interact with the changing climate.”有一些隐形因素,科学家叫做“反馈机制”。没有人完全了解它们将如何与变化的气候相互作用。第二段接着讲到“There are dozens of other possible‘feedback mechanisms’.Higher temperatures will fuel condensation and increase cloudiness,which may actually damp down global warming.Others,like the‘albedo’effect,will do the opposite.”可能还有许多其他的“反馈机制”。更高的温度将加速凝结,增加朦胧度。实际上,这可能抑制全球变暖。其他的机制,如“反射”效应,其作用相反。可见,“反馈机制”中有的可能促进全球变暖,有的可能抑制全球变暖。A项符合文章的意思。B、C项的内容与文意不符,D项不属于文章中表述的内容。因此本题的正确答案为A。
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