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| GRE作文argumen45和47 |
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【45】The following appeared as an editorial in a wildlife journal.
"Arctic deer live on islands in Canada's arctic region. They search for food by moving over ice from island to island during the course of a year. Their habitat is limited to areas warm enough to sustain the plants on which they feed, and cold enough, at least some of the year, for the ice to cover the sea separating the islands, allowing the deer to travel over it. Unfortunately, according to reports from local hunters, the deer populations are declining. Since these reports coincide with recent global warming trends that have caused the sea ice to melt, we can conclude that the decline in arctic deer populations is the result of deer being unable to follow their age-old migration patterns across the frozen sea."
北极鹿生活在加拿大极地区域的岛屿上。它们全年都通过冰块在岛屿间移动来寻找食物。它们的栖居地局限在那些温暖得足以维持它们所需的植物生长，并且在一年的至少某些时候冷到足以让岛屿间的海面结冰以使它们能够在岛屿间旅行的地方。然而，根据当地猎人的报告，鹿的数量正在下降。由于这一报告正好与最近导致海洋冰面融化的全球变暖趋势同时发生，我们可以得出结论：北极鹿数量的下降是它们无法按它们原有的迁移习惯穿越结冰海面的结果。
【47】Scientists studying historical weather patterns have discovered that in the mid-sixth century, Earth suddenly became significantly cooler. Although few historical records survive from that time, some accounts found both in Asia and Europe mention a dimming of the sun and extremely cold temperatures. Either a huge volcanic eruption or a large meteorite colliding with Earth could have created a large dust cloud throughout Earth's atmosphere that would have been capable of blocking enough sunlight to lower global temperatures significantly. A large meteorite collision, however, would probably create a sudden bright flash of light, and no extant historical records of the time mention such a flash. Some surviving Asian historical records of the time, however, mention a loud boom that would be consistent with a volcanic eruption. Therefore, the cooling was probably caused by a volcanic eruption.
研究历史上气候变化的学者发现在六世纪中叶，地球突然变冷了很多。尽管那个时期很少有历史记录被保存下来，一些在亚洲和欧洲所发现的记录提到了太阳变暗和极度的寒冷。要么是巨大的火山喷发，要么是撞击地球的大型小行星导致地球大气形成一大片尘埃云层，这阻止了一定的阳光导致全球温度显著下降。然而，大型小行星的撞击可能产生突然的强闪光，而现存的那时的历史记录中没有提到过这样的闪光。然而那时遗留下来的一些亚洲历史纪录提到过与一次火山喷发相一致的巨大隆隆声。因此，那时的温度下降多半是火山喷发导致的。 |
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