The vast ice sheets of Greenland and Antarctica are melting faster than previously thought, and that melting is accelerating, ac

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问题     The vast ice sheets of Greenland and Antarctica are melting faster than previously thought, and that melting is accelerating, according to a new report that verifies 18 years of melting via two independent techniques. Left unchecked, the extra water dumped into the oceans could push average global sea level six inches higher by 2050, the report finds. That would mark the ice sheets as the largest contributors to sea level rise, outstripping(超过)melting from Earth’s two other huge, frozen reservoirs, mountain glaciers and polar ice caps.
    The new estimate of ice sheet melting—and the subsequent rise in sea level—outstrips more modest figures offered by the International Panel on Climate Change in 2007, the last time that international body published a comprehensive assessment of the ice sheets. "It’s going to be a concern for people in coastal areas," said Isabella Velicogna of the California Institute of Technology and NASA’s Jet Propulsion Laboratory, a co-author of the report online at Geophysical Research Letters. While six inches of additional sea height may sound small, the increase will distribute unevenly across the globe, Velicogna said, and disproportionately(不匀称地)impact low-lying countries like Bangladesh.
    The study used two techniques to measure the melting of the ice sheets. The most thorough data set, from 1992 through the present, employed satellite radar readings of ice movement, soundings of ice thickness, and other grown-based observations to build a complete picture of the size of the ice sheets from month to month. The second technique drew on unique twin satellites, together called Grace, which measure minute differences in gravity over the entire Earth. The Grace satellites, an acronym for Gravity Recovery and Climate Experiment, were launched by NASA and the German Aerospace Center in 2002.
What can we learn about the second technique to measure the melting of ice sheets?

选项 A、The technique drew on twin satellites and a ground-based equipment.
B、The satellites used were called Gravity Recovery and Climate Experiment.
C、The Grace satellites were launched by the German Aerospace Center in 2012.
D、The technique can’t measure minute differences in gravity over the entire Earth.

答案B

解析 由题干中的the second technique定位到第三段第三、四句。文中指出这种独特的双卫星叫做Grace,并指出Grace卫星是GravityRecovery and Climate Experiment“重力量测及气候监控卫星”的缩写。
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