Answer:
What can you catch but not throw?
I usually wear a yellow coat. I usually have a dark head. I make marks wherever I go.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.
A precious fluid, thicker than water.
Man walks over, and man swims under. In times of war, it can be burned asunder. What is it?
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.