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当今美国航天飞机火箭助推器的宽度,和两千年前罗马的战马有什么关系吗?你一定会笑着说:“没有关系,两者八竿子打不着,简直是风马牛不相及!”恭喜你,答错了!两者还真有密切关系。现代铁路两条铁轨之间的标准距离是四英尺又八点五英寸。为什么会这样?原来,早期的铁路是由建电车的人所设计的,而四英尺又八点五英寸正是电车所用的轮距标准。那么,电车的标准又是从哪里来的呢?最先
Does the width of the rocket boosters in the U.S. space shuttle today have anything to do with Roman horses two thousand years ago? You must smile and say, “It does not matter. ! ”Congratulations, wrong! The two are really closely related. The standard distance between modern railroad tracks is four feet and eight and a half inches. Why did this happen? Earlier, the early railways were designed by people who built trams. Four feet and 8.5 inches were the track standards for trams. So, the tram standards come from? First