If you are visiting a city in China with several subway lines, although you may see some signboards like below, but sometimes you may can’t find where the subway station is due to some complex situation.
At such moment, I recommend you to ask the hospital Chinese to find your way. For example, you may ask them:
“Excuse me, where is Line 7?”
You don’t need to ask them “7号线地铁站在哪里“. If they know it, they will tell you the nearest subway station.
But in the case that you want to find the specified subway station, you can ask like this:
“请问, 南京东路地铁站 在哪里?”
“Excuse me, where is East Nanjing Road Subway Station?”
Generally, you don’t need to tell them the subway line number because every subway station is unique and you can just tell others the subway station name.