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  3. The sudden up thrust of warm, moist air into the terrible cold of the frozen heights is what creates thunder. The sudden stronge

The sudden up thrust of warm, moist air into the terrible cold of the frozen heights is what creates thunder. The sudden stronge

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问题     The sudden up thrust of warm, moist air into the terrible cold of the frozen heights is what creates thunder. The sudden stronger rubbing together or two unlike forces (very warm air against very cold air) develops a kind of electricity called "static electricity". Its charges pro duce lightning and thunder. (46)Thus the violence of the thunderstorm is an almost direct result of millions of warm water drops being thrown into compatible masses of ice crystals—hitting them, rolling over them, melting them, or being frozen by them into snow or hail.
    Exactly how the electric charge is developed by the many, complex forces of this battle of heat and cold is still a matter of opinion. Some scientists think the action of wind against the rain is the principal factor. (47)These scientists believe the wind tears off the outer surface of each falling drops, like pulling a sweater over a child’s head, making a fine negative charge while leaving the main part of the rain drop positive. Other scientists believe that the friction of snow crystals breaking in the wind sets up the electrical charge. In reality it may well be all these factors—and more—that combine to do the work.
    (48)In any case, huge masses of electrically charged raindrops and hailstones become sorted into positive and negative reserves of electrical energy at different parts of the thundercloud, creating between them fields of very great extremes. When the resistance between these fields breaks down, the energy that is suddenly discharged is lightning.
    I do not know of any case of lightning directly causing an airplane accident, Cattle and sheep are more likely to be struck by lightning than are airplanes or houses. There is a recorded case that occurred on a mountainside in the western part of the United States in which one bolt of lightning killed 835 sheep. (49)Evidently the hard, dry earth offered more resistance to the lightning than the route of traveling from the ground, up one leg of an animal, through its moist’ body, and down another leg.
    A person’s chances of being killed by a thunderstorm are not very great. In the United States an average of one person in 265,000 dies as a result of a thunderstorm. Today houses, ships, airplanes, and electric power lines are well protected against lightning, and the risk is decreasing. Even a man whose work exposes him almost daily to lightning can do something about it. (50)Despite the saying that one never knows if lightning strikes him, a person can sometimes feel the bolt coming and, if quick enough take protective action in time.

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答案这些科学家认为，风把落下的每滴雨点的外层表面刮掉，就像从小孩子头顶把运动衫扒掉一样，这样风给雨点的主体充了正电，而同时又给雨点充了少许负电。
解析 这是一个简单复合句，句型是：scientists believe(that)the wind tears off…like pulling...making...while leaving..."主句是scientists believe，后面的宾语从句中省略了连词that。在这一从句中，like pulling a sweater over a child’s head是介词短语作状语；分词短语making a fine negative charge作结果状语，while leaving...是表示对比的分词短语作状语。句中"make a negative charge"是"冲负电"的意思；fine作"细微的"、"极少的"讲。
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