Brush the outside, biting and inside surfaces.

牙齿外侧，咬口面，以及牙齿内侧。

And, finally, brush the inside surface.

最后，刷牙齿内侧。

Some of this light exits the droplet, but a significant portion reflects off the inside surface, like a tiny mirror.

其中一些光从液滴中射出，但很大一部分从内表面反射，就像一面小镜子。

Reflection: A Bounce Inside the Droplet After being refracted and dispersed, the light then hits the inside surface of the water droplet.

反射：水滴内部的反射经过折射和分散后，光线照射到水滴的内表面。