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  3. The concept of obtaining fresh water from icebergs that are pulled to populated areas and dry regions of the world was once trea

The concept of obtaining fresh water from icebergs that are pulled to populated areas and dry regions of the world was once trea

admin2013-05-19  77
问题     The concept of obtaining fresh water from icebergs that are pulled to populated areas and dry regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being considered quite seriously by many nations, especially since scientists have warned that human race will outgrow its fresh water supply faster than it runs out of food.
    Glaciers are a possible source of fresh water that has been overlooked until recently. Three quarters of the Earth’s fresh water supply is still tied up in glacial ice, a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1,000 years. Floating on the oceans are 7,659 trillion metric tons of ice encased (包围) in 10,000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctica.
    Huge glaciers that stretch over the shallow continental shelf give birth to icebergs throughout the year. Icebergs are not like sea ice, which is formed when the sea itself freezes; rather, they are formed entirely on land, breaking off when glaciers spread over the sea. As they drift away from the polar region, icebergs sometimes move mysteriously in a direction opposite to the wind, pulled by subsurface currents. Because they melt more slowly than smaller pieces of ice, icebergs have been known to drift as far north as 35 degrees south of the equator in the Atlantic Ocean. To corral them and steer them to parts of the world where they are needed would not be too difficult.
    The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the funneling (通过漏斗般流过) of fresh water to shore in great volume. But even if the icebergs lost half of their volume in hauling, the water they could provide would be far cheaper than that produced by desalinating (融化海水), or removing salt from water.
According to the passage, icebergs sometimes move in a direction opposite to the wind______.
选项 A、for unknown reasons
B、owing to the force of wind
C、because of the melting of ice due to the pull
D、due to the currents beneath the sea level
答案D
解析 根据题干中的in a direction opposite to the wind将本题出处定位到第三段第三句。该句中提到，icebergs sometimes move mysteriously in a direction opposite to the wind，pulled by subsurface currents(冰山有时会在底层洋流的推动下颇为神秘地逆风移动)，[D]中的the currents beneath the sea level是对subsurface currents的同义转述，故答案为[D]。
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