radial quantum number

例句：

1. 1. The radial velocity is the speed of the object moving in a circle.
   径向速度是物体沿圆周运动的速度。
2. 2. The radial symmetry of the planets is due to their rotation around their axis.
   行星的径向对称性是由于它们围绕其轴旋转形成的。
3. 3.The radial expansion of the universe is caused by the expansion of space itself.
   宇宙的径向扩张是由空间本身的膨胀引起的。