赤铁矿能用于炼铁的主要成分是氧化铁，其余都是杂质，某地产赤铁矿含杂质35％，问5000吨矿石中含杂质多少吨？能用于炼铁的氧化铁成分占多少吨？
参考答案：
解：该赤铁矿含氧化铁为：
5000吨×（1-35％）＝3250吨
含杂质为：5000吨×35％＝1750吨或5000吨－3250吨＝1750吨
答：5000吨矿石中含杂质1750吨，能用于炼铁的氧化铁成分占3250吨。
| 完形填空。 Charlie Leng spent a few months saving up (积蓄) seven dollars. He wanted to 1 a model plane and went to the shop with the money. On the way, Charlie 2 a little boy crying on a corner of the street. "_ 3 are you crying?" Charlie asked. "Three big boys _ 4 _ my four dollars just now,"the boy said. "I was 5 to buy some exercise books, but now I can't. " Charlie thought of the 6 dollars in the pocket. He thought of the model plane and the poor _ 7 Charlie wanted to walk away, 8 he did not. 9 he gave four dollars to the boy and went home. Charlie 10_ happy. Do you know the reason? He was happy because the little boy was happy. | ||||
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