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The metre (international spelling) or meter (American spelling) (from the Greek noun μέτρον, "measure") is the base unit of length in the International System of Units (SI). The SI unit symbol is m. The metre is defined as the length of the path travelled by light in a vacuum in 1/299 792 458 seconds.
碼(英文縮寫:yd)是英國的英制單位長度,包括英制英制和美製慣例的測量系統,包括3英尺或36英寸。