One night, Tom's house was on fire, but the fire alram was not working! The fire was big and losses were severe.
Tom, "The fire alarm did not work! Everybody! What are we going to do in the future?"
There was silence among the group as DIck, Harry, Sally, Joe and others pondered. When suddenly...
Harry, "I know! All we have to do is to check the fire alarm 2 days earlier before the next fire happen!"