system of rotating green manure crops

例句：

1. 1.The car is rotating on its axis.
   汽车正在轴上旋转。
2. 2. The machine is rotating parts for the assembly line.
   机器正在为装配线旋转部件。
3. 3. The windmill is rotating slowly in the breeze.
   风车在微风中缓慢旋转。