Good Riddles

Question: A thief enters a shop and threatens the clerk, forcing him to open the safe. The clerk says, "The code for the safe is different every day, and if you hurt me you'll never get the code". But the thief manages to guess the code on his own.

How did he do it?

Question: What is it that after you take away the whole, some still remains?

Question: What's the difference between a well-dressed man on a bicycle and a poorly-dressed man on a tricycle?

Question: At night they come without being fetched, and by day they are lost without being stolen.

What are they?

Question: What is it that no man wants, but no man wants to lose?