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A better way to clean the world s one true kilogram 清洁世界上真正一千克的更好方法 IN SEVRES, on the outskirts of Paris, sealed beneath a triplet of bell jars in the laboratoriesof the Bureau International des Poids et Mesures, sits a small cylinder of platinum-iridiumalloy. 在位于巴黎郊区的塞夫勒市，国际计量局实验室里，一个三层的钟形器皿里密封着一个铂铱合金制成的小圆柱。 Put it on a scale, and it would weigh 1 kilogramwhich is appropriate, since this lump ofmetal is not just a kilogram but The Kilogram, the ultimate reference standard for the waythe Systeme internationale d unites measures mass. 给这个小圆筒称重，你会发现它重1千克，这个重量刚刚好，因为这个金属块不只代表1千克，而代表着千克单位，是国际单位体系中测重的最终参考标准。 Scientists like the metric system partly for its simplicityeverything is based on powers often, which makes calculation easyand partly for the elegance of its foundations. 科学家亲睐公制的部分原因在于其简洁性，即任何物品以十为进制进行测量，方便运算;还有部分原因在于其成立基础很好。 Of its seven fundamental units, six are defined with reference to unvarying constants ofnature: the ampere, the candela, the second, the metre, the kelvin and the mole. | 
