why I cannot see myself in the mirror when it is dark?
为什么黑暗时在镜子里看不到自己
Because a mirror reflects light coming from an object.
因为镜子反射物体发出的光.
But when it's dark, the object will not go off any
但是,当黑暗时物体不发光,
light, therefore, nothing will be seen.
因此,什么都看不见.