一缕阳光从云层缝隙中照射下来。

___A ___ray ___of sunshine shone through a gap in the clouds.

光线从空气进入水中时发生了弯曲。

The ___ray ___of light bent as it passed from air to water.

没有一丝光线能到达洞穴深处。

Not a single ___ray ___of light reached the depths of the cave.