题目内容
A Antarctica has actually become a kind of space station―a unique observa?tion post for detecting important changes in the world's environment. Remote from major sources of pollution and the complex geological and ecological sys?tems that prevail elsewhere,Antarctica makes possible scientific measure?ments 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 theUnited States,Switzerland,andFranceare 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 Mountains,some of them more than 14,000 feet high,divide the continent into two very different regions. The part of the con?tinent 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 theAmericasis 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 disap peared,the western part of the continent would be reduced to a sparse (稀疏的) group of island.
While ice and snow are obviously central to many environmental experi?ments,others focus on the mysterious dry valleys of Antarctica,valleys that contain little ice or snow even in the depths of winter. Slashed (挥砍) 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 blown out by vicious winds that roar down from the polar plateau to the sea. Left bare are spectacular gorges,rippled (起伏的) fields of sand dunes,groups of boulders (卵石) sculptured into fantastic shapes by 100-mile-an-hour winds.
Despite the unearthly aspect of the dry valleys,some scientists believe they may carry a message of hope of the green parts of the earth. Some scien?tists believe that in some cases the dry valleys may soak up pollutants faster than pollutants enter them.
1. What is the best title for this passage?
A. Antarctica and environmental problems
B. Antarctica： earth's earlywarning station
C. Antarctica： a unique observation post
D. Antarctica：a mysterious place
2. What would the result be if the West Antarctic Ice Sheet disappeared?
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 scattered islands.
D. The western part of the continent would be reduced to a sparse group of island
3. Why are the "dry valleys" left bare?
A. Because vicious wind blasts the snow away.
B. Because it rarely snows.
C. Because of the global warming trend and fierce wind.
D. Because of the sand dunes.
4. Which of the following is TRUE?
A. The dry valleys have nothing left inside.
B. The dry valleys never held glaciers.
C. The dry valleys may carry a message of hope for the green.
D. The dry valleys are useless to scientists.
1. A主旨大意题。本文主要介绍了南极洲由于其独特的地理位置和特点，现在成了监察世界环境变化的观察哨和空间站。故A项为最佳答案。
2. D细节理解题。根据第三段最后一句可知答案为D项。
3. C细节理解题。根据第四段内容可知，the global war?ming trend和100-mile-an-hour winds造成了这种现象。故选C项。
4. C细节理解题。根据最后一段第一句可知答案为C项。
