A three-dimensional object cannot be built from two-dimensional objects?

Answer 1

false

Actually, the statement is true.

You can imagine a 3-d object being made up of a lot of 2-d objects stacked on top of one another. But remember that, by definition, a 2-d object has no thickness (or, in this case, height).

Height of one 2-d obect = 0

so height of n such objects = n*0 = 0

So a stack, no matter how many objects you use, will remain 0. And so you are not building up a 3-d object.

Alternatively, you could imagine a cube (3-d) being built up from 6 square faces (2-d). Except that this is just the shell of the 3-d object, not the 3-d object itself.