你必须准确地计量长度。
埃及人很可能用不同长度的24小时来计量他们的一天。
The Egyptians probably measured their day in twenty-four hours of unequal length.
他们把公尺的长度规定为经过巴黎的子午线长度的一定比例，而这条子午线长度的精确计量(以“突阿斯”为单位)还在进行中。
The metre was to be defined as a fraction of the Paris meridian whose precise measurement (in toises) was under way.
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