Good Riddles

Question: It takes ten men ten hours to build a certain wall. How long does it take five men to build the same wall?

Question: Can you think of a crime that is punishable if attempted but not punishable is actually committed?

Question: How many letters are in the answer to this riddle?

Question: When you're given one, you'll have either two or none?

Question: I can be dropped from the tallest of buildings and survive,but drop me from the smallest ship and I won't.What am I?