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 island.
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 roars 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.
1. What is the best title for this passage?
[A] Antarctica and environmental Problems.
[B] Antarctica: Earth's Early-Warning 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 cluster of Islands.
3. Why are the Dry Valleys left bare?
[A] Vicious wind blasts the snow away.
[B] It rarely snows.
[C] Because of the global warming trend and fierce wind.
[D] 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 verdant.
[D] The " Dry Valleys" are useless to scientists.
答案詳解
1. A 南極洲和環(huán)境問題。B. 南極洲：地球最早的報警戰(zhàn)。C.南極洲：獨一無二的觀察哨。D. 南極洲：神秘的地方。三項都是總內(nèi)容眾的組成部分。
2. D 大陸西部成為一群島嶼。第三段“橫斷南極的山脈，有的高達一萬四千多英尺，把這大陸分成情況各異的兩個地區(qū)。山脈以東的大陸部分是由差不多兩英里厚的冰層覆蓋的高原;山脈以西，即美洲以南的半個大陸也為冰層所覆蓋。可是，這里冰層覆蓋在大大低于海平面的巖石。如果西南極洲冰層消失，那這大陸西部將成為稀疏的島群。”A. 大陸西部將小時。B. 大陸西部縮小。 D. 大陸西部將成為分散的島嶼。
3. C 因為地球變暖和狂風勁吹。在第四段：“……這些干谷甚至在寒冬季節(jié)也很少有冰雪。它們插在南維多利亞陸地的山脈中，一度曾有從極地高原到羅斯海的深度為9000英尺的冰河?，F(xiàn)在冰河已不存在，很可能是冰期之后一萬年間地球變暖的結果。即使落入干谷的雪也被從極地高原咆哮入海的邪惡狂風吹散了。留下來的是裸露的壯觀的峽谷，沙丘起伏的原野，被時速一百英里的大風雕刻成奇形怪狀的大礫石，形成與世隔絕的荒涼景象。”A. 邪惡的狂風吹走了雪。B. 它很少下雪。D.沙丘。這三項只是干谷現(xiàn)象的一部分。
4. C 他們可能為地球上綠色地區(qū)帶來了希望的信息。答案是第五段第一句“盡管干谷具有神秘的一面，科學家卻相信他們可能為地球上蔥綠的地方帶來了希望的信息。”A.干谷內(nèi)什么都沒有留下。B. 干谷內(nèi)從沒有冰河。D. 按照科學家的看法，干谷毫無用處。
