Have you ever heard the story of the four-minute mile? For years people believed that it is impossible for a human being to 1 a mile in less than four minutes until Roger Banister proved it 2 in 1954．Within one year, 37 runners 3 the belief barrier．And the year after that, 300 other runners did the same thing．
What happens if you put an animal in a 4 ? Any animal, big or small, will swim its way through．What happens when someone, who does not know how to swim, falls in deep waters? You 5 ．If an animal who has not learned swimming could 6 by swimming, why not you? Because you believe you will drown while the animal does not．
