从已灭绝的复活节岛棕榈坚果的考古发现中可以看到由波利尼西亚老鼠的牙齿形成的小凹槽。

Archaeological finds of nuts from the extinct Easter Island palm show tiny grooves, made by the teeth of Polynesian rats.

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推测的法向周节与实际测量值不同。影响周节错误的最主要因素是齿轮侧面有凹槽。

It is the difference between theoretical normal pitch and its actual measured value. The major element to influence the pitch errors is the runout of gear flank groove.

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