What do the spirits look like?

Each ghost has a symbolic representation with the time they represent. The Ghost of Christmas Past is described,

like a child: yet not so like a child as like an old man, viewed through some supernatural medium, which gave him the appearance of having receded from the view, and being diminished to a child's proportions.

He represents the choices that Scrooge had made in his childhood to adulthood.

Please submit your question for the other two ghosts one at a time.