It is a composite motion; one cannot rotate purely by the forearm with the fingers staying passive, nor if the fingers are overactive and the forearm is inactive.

• 它是一个复合的动作;人们不能在手指处于被动状态时仅旋转前臂,如果手指过度活跃,前臂变得无活性,也不能旋转前臂。