[解析]
(1)细节理解题。由本文第二段Researchers found the population living in a fjord in the southeast Greenland,which is surrounded by mountains and an ice sheet to the west,and ocean to the east.The sea﹣ice coverage lasts for only around 100 days each year.With sea ice in the fjord becoming smaller because of global warming,the whole group were expected to die out by the end of this century.(研究人员发现这些种群生活在格陵兰岛东南部的一个峡湾,西部被山脉和冰盖包围,东部被海洋包围。海冰覆盖每年只持续大约100天。由于全球变暖,峡湾的海冰越来越小,预计整个种群将在本世纪末灭绝。)结合第三段But the isolated population has found a way to hunt without sea ice.The group,about 27 adult females,has been isolated from other polar bear populations along Greenland's east coast for at least 200 years.(但孤立的族群找到了在没有海冰的情况下捕猎的方法。这群大约有27只成年雌性北极熊,已经与格陵兰岛东海岸的其他北极熊种群隔离了至少200年)可知,新发现的这一北极熊群体找到了这一种没有海冰的狩猎方式,所以答案为B。
(2)推理判断题。由本文第二段With sea ice in the fjord becoming smaller because of global warming,the whole group were expected to die out by the end of this century.(随着全球变暖,峡湾的海冰变少,预计整个群体将会在本世纪末消亡。)可知由于海冰变少,峡湾里的北极熊群里就可能会面临灭绝。所以答案为D。
(3)推理判断题。由本文倒数第二段For example,when members of the group went out of the fjord,the ice on which they sat sometimes got caught in the rapid water flow. "Whenever this happened,they would get stuck and then,they would have to jump off,swim to the beach and walk back home empty﹣handed," says lead author Kristin Laidre,an animal ecologist at the University of Washington in Seattle.(例如,当北极熊群体的成员走出峡湾时,它们坐在上面的冰有时会被湍流的水流所困住。"每当这种情况发生时,它们就会被困住,而不得不跳下,游到海滩,空手回家,"西雅图华盛顿大学的动物生态学家Kristin Laidre说道。)可知如果北极熊群体走出峡湾,它们就会陷入困境。所以答案为C。
(4)标题判断题。由本文第一段Polar bear generally need sea ice to survive,so the discovery is raising hopes that some kinds of the polar bears might survive the loss of sea ice caused by global warming.(北极熊通常需要海冰才能生存,因此这一发现让人们燃起了希望,即某些种类的北极熊可能会在全球变暖导致的海冰减少中幸存下来。)可知本文主要讲述了研究者发现北极熊可能会在全球变暖导致海冰流失中幸存下来。所以以A.Polar bear population can survive without sea ice(北极熊种群可以在没有海冰的情况下生存)作为题目最合适。所以答案为A。