Good Riddles

Question: Draw, fire, or fill me;
I'm still empty.

What am I?

Question: Had by few but treasured by all,
I'm on the inside and outside and I make men fall.

What am I?

Question: what did the postman say to the mailbox?

Question: A town builds a bridge, but this bridge can only hold three people at a time or it will collapse. One night, a baker, a flourist and a butcher go on the bridge, and it collapses. Why did it collapse?

Question: What do you call 2 Us?