invariable axis

例句：

1. 1. The axis of the planet is determined by its rotation around the sun.
   行星的轴线由其绕太阳旋转确定。
2. 2.The axis of symmetry is the line that divides a figure into two equal parts.
   对称轴是将图形分成两个相等部分的线。
3. 3. The axis of rotation is the point where the object moves or rotates.
   旋转轴是物体移动或旋转的点。