2. 外语
  3. Oil pools are valuable underground accumulations of oil, and oil fields are regions underlain by one or more oil pools. When an

Oil pools are valuable underground accumulations of oil, and oil fields are regions underlain by one or more oil pools. When an

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问题     Oil pools are valuable underground accumulations of oil, and oil fields are regions underlain by one or more oil pools. When an oil pool or field has been discovered, wells are drilled into the ground. Permanent towers, called derricks, used to be built to handle the long sections of drilling pipe. Now portable drilling machines are set up and are then dismantled and removed. When the well reaches a pool, oil usually rises up the well because of its density difference with water beneath it or because of the pressure of expanding gas trapped above it. Although this rise of oil is almost always carefully controlled today, spouts of oil, or gushers, were common in the past. Gas pressure gradually dies out, and oil is pumped from the well. Water or steam may be pumped down adjacent wells to help push the oil out. At a refinery, the crude oil from underground is separated into natural gas, gasoline, kerosene, and various oils. Petrochemicals such as dyes, fertilizer, and plastic are also manufactured from the petroleum.
Which of the following can be inferred from paragraph 3 about gushers?
选项 A、They make bringing the oil to the surface easier.
B、They signal the presence of huge oil reserves.
C、They waste more oil than they collect.
D、They are unlikely to occur nowadays.
答案D
解析
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