Because it is a flow concept, production is measured as a "rate of output per period of time".
因为“生产”是一个“流量的概念”，所以以“一段时间里的生产率”来计量它。
However, Liyin is a historical concept as it was formed through a historical period of time.
然而“吏隐”是个历史的概念，它的形成是一个历时性的过程。
The concept of cutting tool life-cycle management was put forward, and divided it into four phases: planning period, input time, serviceable life and discarding period.
提出了刀具全生命周期管理的概念，将刀具全寿命周期管理划分为计划期、投入期、使用期、报废期四个阶段。
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