【正确答案】
C
【答案解析】[听力原文] Among global warming's most frightening threats is the prediction that the polar ice-caps will melt, raising sea level so much that coastal cities from New York to Los Angles to Shanghai will be flooded. Scientists agree that the key player in this scenario is the West Antarctic ice sheet, a Brazil-size mass of frozen water that is much as 7000 feet thick. Unlike floating ice shelves which have little impact on sea level when they break up, the ice sheet is anchored to bedrock, will blow the sea surface. Surrounded by open ocean, it is also vulnerable, but Antarctic experts disagree strongly on just how unstable it is. Now, new evidence reveals that all or most of the West Antarctic ice sheet collapsed at least once during the past 1.3 million years, a period when global temperatures probably were not significantly higher than they are today. And the ice sheet was assumed to have been stable. In geological time, a million years is recent history. The proof, which was published last week in Science, comes from a team of scientists from Uppsala University in Sweden and California Institute of Technology who drilled deep holes near the edge of the ice sheet. Within samples collected from the solid substance lying beneath the ice, they found fossils of microscopic marine plants which suggest that the region was once an open ocean, not solid ice. As Herman Engleheart, a co-author from the California Institute of Technology says, 'The West Antarctic ice sheet disappeared once and can disappear again.' What is one of the most frightening threats of global warming according to the passage? 浏览选项，考生可推断听力文章是关于全球变暖问题的。听力篇章一开始讲到，全球变暖最恐怖的威胁就是冰川融化，海面升高，淹没沿海城市。选项C中的be covered with water对应原文中的be flooded。