Logic Riddles

Question: If one cat is a mother, one cat a sister, one cat an aunt, one cat a cousin, one cat a grandma and one a granddaughter, how many cats are there?

Question: What is it that you have that no one else has?

Question: I sit on a bridge so you might see just how clear the world can be. What am I?

Question: There are three books on a shelf standing side by side. Each book is 10ml thick. The bookworm eats its way through the first page of the first book to the last page of the last book. How far did the bookworm move if it can only move in a straight horizontal line?

Question: In the books of a famous writter, How many letter in Those Books?