Answer:
Never ahead, ever behind, yet flying swiftly past; for a child, I last forever; for an adult, I'm gone too fast. What am I?
I walk on 4 legs in the morning, 2 legs at noon, and 3 legs at night. What am I?
I don't live within a house nor do I live without. Most will use me when they come in and again when they go out.
What can fill a room but takes up no space?
I regularly change shape yet remain a sphere. I am always there but not often seen. What am I?
Often cooked as fillet, this meat comes from an animal that swims underwater.