一杯可乐售价1.8元，商家为了促销，顾客每买一杯可乐获一张奖券，每三张奖券可兑换一杯可乐，则每张奖券相当于（　　）

鲁班造锯

    鲁班是我国古代最负盛名的能工巧匠，也是一位十分伟大的发明家。传说现在木工所用的锯子就是鲁班（发现 发明）的。

    一天，鲁班到一座高山上去寻找木料。突然脚下一滑，他急忙伸手抓住路旁的一丛茅草。手被茅草滑破了，渗出血来。

    “怎么这不起眼的茅草这么锋利呢？”他忘记了伤口的疼痛，扯起一把茅草细细端详，（发现   发明）小草叶子边缘长着许多锋利的小齿。他用这些密密的小齿在手背上轻轻一划，居然割开了一道口子。

    他想：要是我也用带有许多小锯齿的工具来锯树木，不就可以很快把木头锯开了吗？那肯定比用斧头砍要省力多了。

    于是，他就请铁匠师傅打制了几十根边缘上带有锋利的小锯齿的铁片，拿到山上去做实验。果然，很快就把树木锯断了。

    鲁班给这种新发明的工具起了一个名字，叫做“锯”。  

    Mick Polly, the owner of a toy store, lives with his daughter Carolina in Kentucky, USA. People also call him the Bike Man because over the past few years, Mick has built hundreds of bikes for needy kids.

    One day in 2012, a 13-year-old boy with a broken bike walked by Mick's house. "I was working in my garage (车库), and he asked if I could repair (修理) it," said Mick.

    The boy's bike had broken wheels (车轮). Mick posted (发布) a picture on Facebook, asking his friends if they had the parts he needed. One friend saw the picture and gave away two used bikes. Mick took parts from each to build a new set of wheels for the boy.

    Soon after, Mick repaired a bike for the boy's brother and one for his sister. During the year, he repaired lots of bikes for kids whose parents didn't have enough money for new ones.

    People are throwing away (扔掉) bikes every day," said Mick.

    Mick puts the bikes and bike parts in his garage. "I take off the good wheels or the seats and use them," he said.

    Up to now, Mick has repaired hundreds of bikes and given away almost 700 newly repaired bikes. They're free, but the kids must agree to try their best to study in school.

    Mick also hopes the bikes will get kids off the sofa. "When I was growing up, we all rode our bikes," he said. "Hopefully these kids can get some exercise."

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