Question

why we cannot see things kept in dark

Answer 1

In the human eye, there are rods and cones. These allow you to see. Rods help you see when there's little light, but that comes at the expense of your color vision. Cones let you see in bright light with color. Animals that see well in the dark have more rods, or their equivalent of rods. Therefore, it's almost certain that these animals don't see colors quite as well as us, but I might be wrong.



Hope it will help you

Answer 2

only when light falls on an object we can see that.
In dark there is no light rays fall on any object so we can't see that