Good Riddles

Question: I always murmur but never talk, i always run but never walk, and I have a bed but I don't sleep. What am I?

Question: What goes up but never go down?

Question: What do you get when you cross an elephant and a fish?

Question: Why was the woman fired from the car assembly line?

Question: Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a sports car; behind all of the others is bicycles. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 2, revealing a bicycle. He then says to you, "Do you want to pick door No. 3?" Is it to your advantage to switch your choice?