Good Riddles

Question: A woman is in the hospital for a routine procedure. The doctor leaves the room locking the door before he goes, the woman is alone. The doctor comes back to find the woman has died and there is another person is in the room. The door was still locked.
How is this possible?

Question: There is a chain nailed to the wall. The chain is 10 feet long and the center of the chain dips down 5 feet from where each side of the chain is nailed to the wall. How far are the 2 ends of chain from each other?

Question: My boots can fit though the green glass doors but my shoes cannot. Sea weed can fit but algae cannot. A tree can fit but a forest cannot. The moon can fit but a feather cannot. Why is this?

Question: Each morning I appear to lie at your feet. All day I will follow no matter how fast you run. Yet I nearly perish in the midday sun. What am I?

Question: Every time a man lies his nose grows to 150 percent of its size. Every time he tells the truth it shrinks to 50 percent of its size.

What will happen if he alternates between lies and the truth?