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  3. The polar vortex (极地旋风) currently sweeping across the North American continent is bringing with the scenes usually associated wi

The polar vortex (极地旋风) currently sweeping across the North American continent is bringing with the scenes usually associated wi

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问题     The polar vortex (极地旋风) currently sweeping across the North American continent is bringing with the scenes usually associated with the Arctic or Antarctic. Massive snowfall and violent winds have brought temperatures down to record lows. In some areas of the US, such as the state of Indiana, all but essential emergency vehicles are banned from the roads. People are being urged to remain inside in the warm.
    The human body is not designed for polar cold—most of us live in temperate and tropical climate, where the mercury rarely dips below freezing. There are populations that have adapted to polar extremes—like the Inuit in Arctic Canada and tribes like the Nenets in the north of Russia—but the vast majority of Homo sapiens (现代入) has no experience of living in such sub-zero temperatures. And while our ingenuity and expertise has allowed us to create clothing to withstand all but the most violent Arctic blizzards, polar survival is all about keeping out of the most fearsome cold unless you absolutely have to.
    What happens when we get cold? The human body has several defence mechanisms to try and boost our core temperature when it gets chilly. Our muscles shiver and teeth chatter. Our hairs rise and our flesh forms "goosebumps"—a kind of evolutionary echo from the times when our ancestors were covered in fur. The hypothalamus (下丘脑) , the gland in the brain that acts as your body’s thermostat (恒温器) , stimulates these reactions to keep the body’s vital organs warm, at least until it can find some kind of warmth and shelter.
    The hypothalamus’s mission is to keep the core warm at all costs—sacrificing the extremities if need be. That’s why we feel pins and needles in our fingers and toes in extreme cold—the body is keeping its warm blood close to the centre, constricting blood supply in the outer regions such as the end of our limbs. In extreme cold, and especially if bare skin is open to the elements, this effect can end in frostbite.
    So how do other warm-blooded animals living in such climate cope when we can’t? Polar animals are either covered in winter coats of fur—which traps warm air close to the body—or else large quantities of fat, sometimes inches thick. Fat does not transfer heat very well, so it keeps it inside the body. Humans, with naked skin and relatively little fat, just aren’t built for these environments.
    But we have learned to imitate these qualities. Scientists in Antarctic stations, for instance, dress in layers upon layers, which traps warm air close to the body like fur does.
What can we learn from the first paragraph?
选项 A、The north areas of the U.S. were stricken by the polar vortex.
B、The temperature in the Arctic has dropped to record low.
C、All the vehicles are banned in some areas of the U.S.
D、The local government asked people to stay in warm places.
答案D
解析 细节题。根据题干中的the first paragraph可定位到第一段。该段第一句提到当前横扫北美大陆的极地旋风带来了通常只有南北极才有的景象，第二句提到北美大陆的气温骤降至历史最低，第三句提到美国部分地区禁止除重要急救车辆外的一切车辆上路，最后一句提到(政府)敦促人们待在温暖的室内。四个选项中只有D项描述符合原文，故选D。
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