It was the ambition of an eleven-year old boy in Kansas City to be an engine-driver. Born without arms, he had been to special schools where he learned to use his feet as "hands". He spent all his spare time watching trains and one day his dreams came true. Seeing a deserted engine, the boy climbed in. He had no difficulty in starting it up with his feet. Soon he was traveling along at forty miles an hour. Signalmen could not see the young driver. So they set out to stop the train. Meanwhile the boy reached Missouri, stopped the engine himself, and then made it go backwards. When he was near home, a railway-man caught up with the engine and stopped it. At first he was very angry, but he smiled when the boy said simply, "I like trains. ""Well, I’ m glad you don’ t like planes !" answered the railway-man. What was the ambition of an eleven-year-old boy（）