地下鉄

地下鉄

Subway.

Here, '地下鉄' is used to refer to the mode of transport, the subway, emphasizing the means of traveling to school.

私は地下鉄で学校へ行きます。

I go to school by subway.

In this sentence, '地下鉄' refers to the entirety of the subway network, focusing on its attributes, like convenience.

東京の地下鉄はとても便利です。

The subway system in Tokyo is very convenient.

Here, '地下鉄' is used as a descriptor, modifying '駅' (station) to specify the location as being a subway station.

地下鉄の駅で友達に会いました。

I met my friend at the subway station.