Lucy is at the platform and she's waiting "for the first express train." 露西在站台上，她正在“等第一辆特快列车”。

Express, "express," here means the train that makes the fewest number of stops. 快车(express)，指的是停靠站最少的列车。

Express trains, such as in New York, will only stop at some of the subway stations, not at all of them. 特快列车，像在纽约这样的，只会在几个地铁站停，不会所有站都停。

If you want a subway train that stops at all the stations, you would get what we would call a local train. 如果你想乘一辆每站都停的地铁，你可以乘我们所说的普通列车。

This is true especially in New York City; if you look at their map of the subway, 尤其是在纽约;你看一下他们的地铁地图，

you will see that some subway trains are express, meaning they make fewer stops. They don't stop at every subway station, and some are local. 会看到一些地铁列车是特快列车，这意味着他们会少停几站，他们不会在每个地铁站都停，还有一些是普通列车。