2022年高考英语一轮复习Unit22EnvironmentalProtection单元主题语篇训练.docxVIP

Unit 22单元主题语篇训练 A Meet the longest- living vertebrate （脊椎动物）in the world, the Greenland shark. Found primarily in the very cold waters of the North Atlantic, these slow-swimming sharks can be as big as the largest great whites, reaching up to 21 feet in length. Theyre among the largest of carnivorous （食肉的）fish, and yet grow perhaps only a centimeter or so a year. Such slow growth yet big size is usually an indicator of a long-lived animal. “We only expected that the sharks might be very old, “ Julius Nielsen, at the University of Copenhagen in Denmark, told NPR. But we did not know in advance. And it was, of course, a very big surprise to learn that it was actually the oldest vertebrate animal. ” Imagine being 150 years old before you re ready to have your first child! Imagine being born before the United States was even a reality. For humans 一 who rarely make it to a century mark — it，s difficult to fully understand. Little is known about Greenland sharks, even basics such as where they give birth or how many of them there are, though researchers at a conference at the University of Exeter thought that they may mate in “hidden” Arctic fjords. No one has even witnessed one hunting, though they have been found to have various vertebrate ones in their stomachs such as polar bear, seals, fast- swimming fish and even moose etc. Given the shark，s incredibly long lifespans, scientists are diving into the sea creatures genome, looking for clues. That conference also highlighted the work being done to separate the shark，s longevity gene, with complete DNA information gathered from almost 100 sharks, including some born in the 1750s. Finding such a gene could go a long way in explaining why some vertebrates, like humans, have such limited lifespans. These sharks also serve as swimming history books. Their tissue, bones and DNA could tell us a great deal about the waters of the world from a time before the Industrial Revolution, large-scale commercial fishing and the pronounc