Could anybody explain the difference of these expressions? <br/><br/>A: "Believe you me." <br/>B: "Believe me." <br/><br/>Which one is correct in the following conversation? <br/><br/>"We would never find out what's wrong with it. ( )." <br/>"OK, take it easy. Let's take time and figure it out." <br/><br/>Many thanks for your help.