Answer:
When a doctor hits you with a hammer he is testing this
What gets wetter and wetter the more it dries?
What goes through towns and over hills but never moves?
Controlled by your hands and feet. It would be nothing without a street. What is it?
Securing your documents is easy with these trusty metal objects
I touch the Earth, I touch the sky, but if I touch you, you’ll likely die. What am I?