Unit 1 A land of diversity 课时作业 Ⅰ.阅读 (2020·云南省曲靖市第一中学高考复习质量监测(三))You may already know that more than a million years ago, glaciers, or vast blankets of moving ice, covered one third of the earth. You also may know tens of thousands of years ago, the glaciers started to melt, retreating to their current position in the Antarctic and Greenland. You may even know that glaciers also exist in all the world's great mountain regions. But do you know that glaciers cover about 6 billion square miles of the earth and store about 75 percent of the earth's fresh water? A glacier forms in a cold climate when a winter's snow does not completely melt during the following summer. Snow continues to accumulate and partially melt year after year. As the accumulated snow becomes heavier, the lower layers crushes under the weight and changes into ice. Over time, the mass of ice thickens and moves. The ice is either pulled slowly downhill by gravity—as in the valley glaciers found in the Alps, on the Alaskan coast, and in the Western United States—or forced outward in all directions by its own weight—as in the ice sheets and icecaps covering most of Greenland and Antarctica. During the glaciations (冰川作用), a glacier moves (usually about 3 feet per day). It picks up pieces of rock that cut and polish the land and carve out steep－side valleys. During deglaciation (冰消作用), a glacier withdraws and often leaves large deposits of sand and stones. The process of glaciation and deglaciation formed the Great Lakes in North American during the Ice Ages. Some scientists believe that ice ages similar to those of the past will occur, but they disagree on when this will happen. Other scientists think that global warming will occur instead, melting the glaciers and flooding areas as sea levels rise. No one knows for certain which event will occur, but neither predicts well for mankind. 篇章导读：本文是一篇说明文。文章主要介绍了冰川的一些情况。 1．What happens to a glacier during glaciation? A．It moves. B．It leaves stones. C．It leaves sand. D．It forms the Great Lakes. 答案：A 细节理解题。根据第二段倒数第四句“During the glaciations (冰川作用), a glacier moves (usually about 3 feet per day)．”可知选A。 2．What will happen if global warming occurs instead of another ice age? A．Vast blankets of ice will cover the earth. B．Glaciers in the Antarctic will increase in size. C．Plant and animal life in many related areas will be destroyed. D．A winter's snow may not completely melt during the following summer. 答案：C 推理判断题。根据第三段第二句“Other scientists think that global warming will occur instead, melting the glaciers and flooding areas as sea levels rise.”可推理出全球变暖导致冰川融化，致使海平面上升，将淹没很多地区，因此，相关的动植物将受到毁灭性的打击。故选 C。 3．What is the attitude of the writer towards the argument between scientists in the last paragraph? A．Optimistic. B．Objective. C．Pessimistic. D．Indifferent. 答案：B ... ...
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