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- 2011-1-23
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Many geologists theorize that the trail of volcanic crater and cinder cones along the Snake River plain of southern Idaho was produced as the North American continent slid west-ward over a stationary"plume," a vertical channel through which molten rock rose intermittently from the Earth's core to burst through its crust. Which of the following, if true, tends to support the geologists' theory of how the trail was produced? A the largest crater and cinder cones are on the eastern margin of the trail B The most violent volcanic activity apparently occurred at the western margin of the trail C The crater and cinder cones are on the eastern margin of the trail D The newest crater and cinder cones are on the eastern margin of the trail E The craters and cinder cones on the western margin of the trail generally took longer to form than did those on the eastern margin
答案是D,我真是看不明白。。。
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