题目

When passing through an airport one morning, I caught one of those trains that take travelers from the main terminal(终点站) to their __41__ gates. Free and clean, the trains run __42__ all day long. Not many people consider them __43__, but this Saturday I heard laughter. At the front of the first car, a man and his son were looking out of the window at the __44__. The train had just stopped and the passengers__45__. As the doors closed again, the father said excitedly, “Here we go! Hold on to me __46__! Look!” the father said to his son. “See that pilot? I __47__he’s walk13．本格拉铁路全长约（　　）A．500kmB．1300 kmC．2800 kmD．3600 km