Why human can see black color?

In latest lecture, lecturer give us a question about why people can see black color...and no one can answer this question. We suppose to know this question since secondary school...Therefore, I going to do a revision for this.

Question:

Why people able to see black color object?

We can see the object because it reflect the light into our eyes. But black color can absorb light, it won't reflect any light, then how people see the black color object?

In my research, we able to see red color light, blue color light, green color light....White light is the combination of all light color, but we cannot see black light. It is because black color will absorb the all the light, there is no black color light.

We can see the black color object, but cannot see the black object if in the dark condition. This mean we can see the black color object not because of the reflection of light, but through the contrast of the black color object and other object color. In other words, if the other object color will reflect the red light,blue light, green light and other light to our eyes, then we able to see the black color object.