A single 'light ray' actually doesn't exist. 'Light ray' is only a concept. It is the geometrical visulaization of a beam of light, just for the ease of interpretation and understanding in various physical phenomena in optics.
It is therefore you can see a beam of white. but never a single 'ray of light'.
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You can see a surface because the surface reflects the light that falls on it into tour eyes.
Hence, a surface will appear black if the surface absorbs all the light that fall on it and reflects none.