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1·Which one of the following is the best reason for using variable costing?

下面哪一项是采用变动成本法的最好理由？

2·The plan is made up of 83c251sb one-chip computer and SA4828 integration-chip of SPWM wave signal, which is a simple-structure, low-costing and well-functioned variable frequency controller.

本设计方案采用83c 251sb型号单片机和SPWM波信号发生器s A 4828组成一种结构简单、成本低、功能较好的变频控制器。