某村领导要求信息处理技术员估计该村一池塘中的鱼的大致数量。该技术员想出了一个办法：先从池塘中捕出30条鱼，在每条鱼身上做一记号后，又放回池塘。几天后，再从该池塘中捕出40条鱼，发现其中有2条是有记号的。因此，他估计该池塘鱼的数量大致为 (68) 条(假设这几天内鱼的数量没有变化)。
参考答案：C
解析： 假设该池塘内有X条鱼，从其中取出30条鱼做了记号又放回去，那么池塘内做记号鱼的比例大致为30/X。几天后，从该池塘中取出40条鱼中，有2条有记号，那么，做记号的鱼所占的比例约为2/40=-5%。30/X应与5%相当。所以X大致为30/5%=600条。
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| Once my father and I went to see a circus (马戏团). A family was standing in front of us 1 for tickets. The family had eight children. Their clothes were not 2 but they were clean. They were talking about the clowns (小丑) and elephants excitedly. "I want 3 tickets, eight for children and two for adults (成人)." said the father to the ticket lady. The ticket lady told him the 4 . When he heard that, the man couldn't believe his 5 . He asked again, "How much?" The ticket lady spoke again. The father looked sad. Clearly, he didn't have 6 money. My dad took a $20 bill and dropped it on the ground. Then he 7 the bill, and said to the man, "Sir, this fell out of your pocket." The man knew what was 8 on. He looked into my dad's eyes and took the 9 ."Thank you, thank you, sir. This 10 means a lot to me and my family." We didn't go to the circus that night, but we didn't feel sorry for it at all. | ||||
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