Good Riddles

Question: A man and his son are in a terrible accident and are rushed to the hospital in critical care. The doctor looks at the boy and exclaims "I can't operate on this boy, he's my son!" How could this be?

Question: I have no wings but I fly,
I have no teeth but I bite.

What am I?

Question: The more you work, the more I'll eat.You keep me full, I'll keep you neat. What am I?

Question:

The dirtier I am, the whiter I get,
Leave a mark on me when you stand, I'll leave a mark on you when you sit.

What am I?

Question: Two boys, Trevor and Tyler, are running a 100 meter race. The first time they race Trevor beats Tyler by 5 meters. To make things fair, the next time they race Trevor stands 5 meters behind the starting line.

Who wins the second race (assuming they run the same speed as the first race)?