通读下面的短文，掌握其大意。然后，从每小题的四个选择项中选出可填入相应空白处的最佳选项。

     As a boy I dreamed of flying airplanes.  I told Dad I wanted to be a pilot, he said, "You need to do your job well on the farm first, and  you may realize your dream." The farm was an everyday responsibility (职责)—that  Saturday, Sunday and Christmas too. Every morning I got up at four o'clock to milk and  the cows. After the milk was bottled, my older brothers and I  it to people’s homes. I was paid five cents a bottle. At that time I  that to be successful you have to take care of your responsibilities.
     When I was 16, I signed up for flying lessons. To pay for the lessons I  a small restaurant with some friends. One of our regular  was the president of the Farmers Bank. Every  I got, I talked to him about my dream. One day I told him I  $3,500 to buy my own . He lent me the money so that I could fly people within 150 miles of the airport.
     Twelve years later I was flying people around the world  a pilot of a big airline company.
     After ten years in the company I started my own .
     Today I run a billion-dollar company, but it was on the farm that I learned the principles (原则) that have  me. Hard work and determination do  dreams come true.