As a boy I dreamed of flying air

As a boy I dreamed of flying airplanes. _____（21）I told Dad I wanted to be a pilot, he said, "You need to do your job well on the farm first, and _____（22）you may realize your dream." The farm was an everyday responsibility（职责）——that _____（23）Saturday, Sunday and Christmas too. Every morning I got up at four o' clock to milk and _____（24）the cows. After the milk was bottled, my older brothers and I _____（25）it to people's homes. I was paid five cents a bottle. At that time I _____（26）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 _____（27）a small restaurant with some friends. One of our regular _____（28）was the president of the Farmers Bank. Every _____（29）I got, I talked to him about my dream. One day I told him I _____（30）$3,500 to buy my own _____（31）. 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 _____（32）a pilot of a big airline company. After ten years in the company I started my own _____（33）.Today I run a billion-dollar company, but it was on the farm that I learned the principles（原则）that have _____（34）me. Hard work and determination do _____（35）dreams come true._____.
A、When
B、Though
C、Before
D、Since
【正确答案】：A
【题目解析】：本题考查引导时间状语从句的从属连词的选择。根据上下句逻辑关系的判断，应该选A。句子要表达的意思是：我儿时的梦想是驾驶飞机。当我告诉父亲我想当飞行员的时候，他说“……”A当……时候；B虽然、尽管；C在……之前；D自从……。