| 释义 |
metre In SI units, the base unit used for measuring length, abbreviated to ‘m'. It was once defined as one ten‐millionth of the distance from one of the poles to the equator, and later as the length of a platinum–iridium bar kept under specified conditions in Paris. Now it is defined in terms of the wavelength of a certain light wave produced by the krypton‐86 atom.
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