This paper has proved that a plane curve cis a circle if and only ifc is the locus of a moving point that has a constant second power average of distances from n fixed points.

本文提出了确定内燃机配气机构刚度的三种数据处理方法，并对处理结果作出了分析、比较，确认二次刚度平均法是一种较好的实用方法。

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There are two limitations on the power handling ability of a transistor: average junction temperature and second breakdown.

有两个限制了晶体管的处理能力，功耗：平均交界处的温度和二次击穿。

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Armstrong noted Leopold can play in every situation, including the power play, and ranked second among the Sabres with an average of more than 21 minutes in ice time per game.

WSJ: Sabres trade D Leopold to Blues for 2 draft picks