Axis bulbi internus

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 spindle of the needle is used to hold the thread in place.
   针的纺丝是用来保持线的位置。
3. 3. The axis of symmetry divides the object into two equal parts.
   对称轴将物体分成两个相等的部分。