a sqarepyramid has a ----------as its base.
a road roller is an example of the solid shape-------
a flat shape that can be folded to make a solid shape is called-------

1.

The base of the square pyramid is a square.
In the figure, ABCD is the base of the pyramid which is square.

2.
As the road rollers are solid and in the shape of a sphere, the road roller is a solid sphere.

3.
When we fold the edges of a flat shape , for example folding a sheet of paper to make a cylinder, the internal part of the cylinder is always hallow,. Therefore, we can not make solid shapes by folding a flat shape.