Why I can't coloring, does anyone know how to solve it?

[nauother]

I can’t coloring the road and also some of the buildings. here is my file. thank you
PETA UNDIP.skp (642.8 KB)

[DaveR]

You can’t color them because they don’t have any faces to color.

It’s not flat so you’ll have to do a lot of work to create surfaces.