Answer:
What has six faces and twenty-one eyes?
What has a bell but isn't a church. Is full of air but is not a balloon?
What can be measured but not seen?
My teeth are sharp, my back is straight, to cut things up it is my fate.
My first is a creature whose breeding is unclear. My second, a price you must pay. My whole can be found in the river of Time and refers to events of today.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.