machine; machinery

severe / intense, acute, extreme / violent

part, component, short for 部分品

abrasion, attrition (wearing by friction)

to wear, be worn away

needed, necessary

need, necessity

exchange; swap; give-and-take / (mathematics) commutation

to exchange

器械: a device, an appliance, a mechanism / 機械: a machine, equipment, an apparatus / 器械: a utensil, a tool, an instrument / 器械: a tool for conducting a test or experiment or for measurement