Brain Teasers

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

I have keys but no locks. I have space but no room. You can enter but not go outside. What am I?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

I speak without a mouth and hear without ears. I have no body, but I come alive with the wind. What am I?