We can machine the commutator and voltameter,we have to deliver them to the shop for rectifying.

可以把换向器车光并拉槽。至于电流表与电压表，送车整。

This paper is a study on the invertibility of the commutator of scalar-idempotent elements and scalar-involutory elements of a unitary ring.

本文研究在一个有单位元的环中两个倍幂等元的换位子与两个倍对合元的换位子的可逆性问题。