Riddles

I come once in a minute, twice in a moment, but never in a thousand years

I always run, but never walk. I have a bed, but I don't sleep. I have a mouth, but I don't eat

When you put this in a heavy wooden box, the box will become lighter

. You hear my sound. You feel me when I move. But see me, you never will

I follow you all day long. But when the night or rain comes, I am gone.

I am very heavy, but backwards, I'm not

The more I dry, the wetter I get

A cowboy rides into town on Friday.

He stays two days, then leaves on

Saturday. How can this be?