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  3. Antarctica has actually become a kind of space station—a unique observation post for detecting important changes in the world’s

Antarctica has actually become a kind of space station—a unique observation post for detecting important changes in the world’s

admin2010-07-19  57
问题    Antarctica has actually become a kind of space station—a unique observation post for detecting important changes in the world’s environment. Remote from major sources of pollution and the complex geological and ecological systems that prevail elsewhere, Antarctica makes possible scientific measurements that are often sharper and easier to interpret than those made in other parts of the world.
   Growing numbers of scientists therefore see Antarctica as a distant-early-warning sensor, where potentially dangerous global trends may be spotted before they show up to the north. One promising field of investigation is glaciology. Scholars from the United States, Switzerland, and France are pursuing seven separate but related projects that reflect their concern for the health of the West Antarctic Ice Sheet—a concern they believe the world at large should share.
   The Transantarctic Mountain, some of them more than 14,000 feet high, divide the continent into two very different regions. The part of the continent to the "east" of the mountains is a high plateau covered by an ice sheet nearly two miles thick. "West" of the mountain, the half of the continent south of the Americas is also covered by an ice sheet, but there the ice rests on rock that is mostly well below sea level. If the West Antarctic Ice Sheet disappeared, the western part of the continent would be reduced to a sparse cluster of islands.
   While ice and snow are obviously central to many environmental experiments, others focus on the mysterious "dry valley" of Antarctica, valleys that contain little ice or snow even in the depths of winter. Slashed through the mountains of southern Victoria Land, these valleys once held enormous glaciers that descended 9,000 feet from the polar plateau to the Ross Sea. Now the glaciers are gone, perhaps a casualty of the global warming trend during the 10,000 years since the ice age. Even the snow that falls in the dry valleys is blasted out by vicious winds that roar down from the polar plateau to the sea. Left bare are spectacular gorges, rippled fields of sand dunes, clusters of boulders sculptured into fantastic shapes by 100-mile-an-hour winds, and an aura of extraterrestrial desolation.
   Despite the unearthly aspect of the dry valleys, some scientists believe they may carry a message of hope of the verdant parts of the earth. Some scientists believe that in some cases the dry valleys may soak up pollutants faster than pollutants enter them.
What would the result be if the West Antarctic Ice Sheet disappeared?
选项 A、The western part of the continent would be disappeared.
B、The western part of the continent would be reduced.
C、The western part of the continent would become hidden Islands.
D、The western part of the continent would become a group of smaller Islands.
答案D
解析 大陆西部会分裂成为一群岛屿。第三段“横断南极的山脉，有的高达一万四千多英尺，把这大陆分成情况各异的两个地区。山脉以东的大陆部分是由差不多两英里厚的冰层覆盖的高原；山脉以西，即美洲以南的半个大陆也为冰层所覆盖。可是，这里冰层覆盖在大大低于海平面的岩石下。如果西南极洲的冰层消失，那这大陆西部将成为稀疏的岛群。”
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