3 pairs
Three.
21
A cuboid has 3 pairs of parallel faces.
A diamond has two pairs of parallel lines.
I'm pretty sure it is 12 pairs of parallel lines.
A cuboid has 3 quartets of parallel lines. Each quartet gives rise to six pairs. So, in all there are 18 pairs of parallel lines.
3 pairs
3 pairs
Three.
21
4
A cuboid has 3 pairs of parallel faces.
A diamond has two pairs of parallel lines.
Three.
A rhombus has 2 pairs of parallel lines.
A regular dodecagon has six pairs of parallel lines.