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网校名师24小时在线答疑解惑直播
名师大咖面对面，有问有大收获多。Newspapers often tell us of floods in some parts of the United States.
Nearly every year on the great central drainages heavy rains and melting snow cause the waters to pour out the mountains and plains, to turn brooks into torrents, and to swell quiet streams into wild uncontrolled rivers. From Cairo to New Orleans, and from Pittsburgh to Paducah, the cry "River rising!" is a familiar yet fearful voice. . . When the rivers sometimes become too high or too swift to be controlled communities are flooded, families flee from their homes, croplands are washed out, and transportation comes to a halt. Hunger, disease, and death follow the wild waters.
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