Good Riddles

Question: I can be one, I can be two. I can be Open, Closed, Empty or Full. I can be Bare, but never a Bear. What AM I??

Question: in all of written history I won't show up at the end of a sentence but I will be there in the end . . .

Question: Act in my name, and thus remove me. What am I?

Question: How do you put a giraffe in a fridge? Put it in and shut the door. How do you put a elephant in a fridge? Take the giraffe out and put the elephant in. There's this animal party all animals are there besides for one what animal is not?

Question: What comes down and never goes up?