Logic Riddles

Question: What can be dying but not be dying?

Question: I am unseen but all people know of me. I am intangible yet sharper than any sword. I come from nothingness but can fell even the mightiest kings.

Question: There is a man dead in the middle of a vast oval, and there was a plane flying in the sky. With an unopened package beside him, how did he die?

Question: What has been found to have no beginning, middle or end; it eats away everything, but makes life for us all?

Question: Romeo and Juliet are dead. The only evidence of their death is in their house, and it is some shattered glass and a puddle of water. The only furniture in the house is a bed, a dresser and a bookshelf. The house is next to a railroad track. Their only pet was a cat. How did they die?