多年来,长度的科学标准曾是一根金属棒,这根金属棒保存在巴黎附近的有温度调节的地下室里。
For many years, the scientific standard of length was a metal bar kept in a temperature controlled vault near Paris.
多年来,长度的科学标准曾是一根金属棒,这根金属棒保存在巴黎附近的有温度调节的地下室里。
For many years, the scientific standard of length was a metal bar kept in a temperature controlled vault near Paris.
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