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两个两位数的十位上的数字相同,其中一个两位数的个位上的数字是6,另一个两位数的个位上的数字是4,它们的平方差是220,求这两位数..

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解: 设这个两个数的十位上的数字是x,则这两个两位数是(10x+6)和(10x+4), 由题意得:(10x+6)2-(10x+4)2=220 解这个方程得:x=5 答:这两个两位数分别是:56和54.

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    There were three big fish in the lake. One of them, Demo, was wise; another one, Jimmy, was half-wise; Martin, the third one, was stupid.

    Some fishermen came to the bank of the lake with their nets. The three fiss saw them.

    Demo decided at once to leave, to make the long and difficult trip to the ocean. He thought, "I won't discuss with these two about this. They love this place so much that they call it home and will stay on. How silly they are! They still haven't realized we are in great danger now. Their ignorance will cost them their lives."

    Seeing the wise fish had left, Jimmy thought, "My guide has gone and now I've lost my chance to escape." He felt sorry for it and then thought, "What can I do to save myself from these men and their nets? Perhaps I should pretend(假装)to be already dead, giving myself totally to the water."  So he did that. He went up and down with the water, helpless, within arm's reach of the fishermen.

    "Look at this! The best and biggest fish is dead." One of the men lifted him by the tail, and threw him up on the ground. He rolled(滚动)over and over and moved secretly toward the water, and then, back in.

    The third fish was aimlessly jumping about, trying to escape with his speed and cleverness. The net, of course, finally closed around him, and as he lay in the hot frying-pan bed, he thought, "If I get out of this, I'll never live again in the limits of the lake. Next time, the ocean! I'll make it my home."