什么是自行车
bicycle
Lightweight, two-wheeled, steerable machine that is propelled by the rider. The wheels are mounted in a metal frame, and the front wheel is held in a movable fork. The rider sits on a saddle and steers by handlebars attached to the fork, propelling the bicycle by two pedals attached to cranks that turn a driving sprocket. An endless chain transmits power from the driving sprocket to a back-wheel sprocket. A heavy pedalless form built in 1818 was propelled simply by the rider paddling his feet against the ground. In 1839 the Scottish blacksmith Kirkpatrick Macmillan (1813-1878) built a bicycle propelled by pedals, cranks, and drive rods; he is widely credited with inventing the bicycle. Important innovations were introduced by Pierre and Ernest Michaux in France in 1861, and by 1865 their company was manufacturing 400 vélocipèdes a year. A lighter version produced in England in 1870 (nicknamed the “penny-farthing”) featured a large front wheel and small back wheel. By the 1890s the standard bicycle design was established, and with the smooth ride enabled by the new pneumatic tires its popularity exploded. 20th-century improvements included lighter frames and improved gears and brakes. Widely used throughout the world, it is a basic means of transportation in many countries. See also bicycle industry.
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用之不竭是什么意思?
意思是:竭:尽。无限取用而不会使用完。成语名字:用之不竭成语发音:yòngzhībùjié成语解释:竭:尽。无限取用而不会使用完。成语出处:宋·苏轼《前赤壁赋》:“唯江上之清风,与山间之明月,耳得之而为声,目遇之而成色,取之无禁,用之不竭。”常用程度:常用成语感情色彩:中性成语...
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言论风生是什么意思?
意思是:形容言谈议论时兴致很高,气氛活跃。成语名字:言论风生成语发音:yánlùnfēngshēng成语解释:形容言谈议论时兴致很高,气氛活跃。成语出处:清·袁枚《新齐谐·赵李二生》:“[书生]邀入坐,言论风生。”成语繁体:言論風生常用程度:一般成语感情色彩:中性成语成语用法:...
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遗臭万载是什么意思?
意思是:死后恶名流传,永远受人唾骂。成语名字:遗臭万载成语发音:yíchòuwànzǎi成语解释:死后恶名流传,永远受人唾骂。成语出处:南朝·宋·刘义庆《世说新语·尤悔》:“[桓温]既而抚枕起曰:既不能流芳后世,亦不足复遗臭万载邪!”成语繁体:遺臭萬載常用程度:一般成语感情色彩...
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高攀不上是什么意思?
意思是:不能同等与地位、名誉较自己高的人结交或攀亲成语名字:高攀不上成语发音:gāopānbùshàng成语解释:不能同等与地位、名誉较自己高的人结交或攀亲成语出处:李六如《六十年的变迁》第一章:“你们钟府上是做官的仕宦之家,我们做买卖的,恐怕高攀不上吧?”常用程度:...