摘要
想在大城市里到处走走，你会用什么方式呢？你会骑自行车、搭公交车，或坐出租车？或者你干脆步行。在很多城市中，搭捷运或地铁是一种受欢迎的通勤方式．我们来看看世界上几个著名的地铁系统吧。
How do you get around a big city？ Do you ride a bike, a bus, or take a taxi？ Or maybe you just walk. In many cities, a popular way to travel is by metro or subway. Let＇s look at some famous metro systems around the world.
