rotation

风扇的旋转速度可以调节。

You can adjust the speed of the ___rotation of the fan.

网球选手的击球有很强的上旋。

The tennis player's shot has a strong topspin ___rotation.

医院实行护士轮班制度，每两周更换一次工作时段。

The hospital has a ___rotation system for nurses, changing shifts every two weeks.