speed of light circle

例句：

1. 1.The speed of light is the fastest known propagation speed in the universe.
   光速是宇宙中已知的最快传播速度。
2. 2.The speed of light is a fundamental constant in physics.
   光速是物理学中的一个基本常数。
3. 3. The speed of light is so fast that it can travel through space in just one second.
   光速如此之快，可以在一秒钟内穿越太空。