填空题
[听力原文]11-15
Thirty years ago, when I was a small boy, my father arranged me to spend two summer vacations at a farm in South Dakota. He thought it would be good for me, and he was right. It taught me a great deal about the importance of independence. The people who lived there were practically self-sufficient. They raised sheep for wool, wove it into cloth, and built their cabins from wood. The place was so isolated that the owner’s daughter, who must have been in her early twenties, said that she had never been away from home or seen a train.