Answer:
You fill it and it empties, A metaphor for plenty, Depending on what half you see, It's either full or empty
The part of the bird, that is not in the sky, Which can swim in the ocean and always stay dry. What is it?
Man's most important invention.
Come up and we go, Go down and we stay.
What type of drink is usually added to cereal in the morning?
I am a rock group with four members. All dead one was assassinated.