Good Riddles

Question: One female dog goes in and there are no other dogs in there so why did dogs come out?

Question: When is a door not a door?

Question: Only one color, but not one size, Stuck at the bottom, yet easily flies, Present in sun, but not in rain, Doing no harm, and feeling no pain. What am I?

Question: What flies without wings?

Question: At night they come without being fetched, and by day they are lost without being stolen.

What are they?