How do I say 'subway'?

地铁 is the backbone of urban transportation in China — every major city has a system, and they are clean, efficient, and mostly bilingual in signage. The vocabulary you need:

• 几号线 — which line. Metro lines are numbered in Chinese: 一号线 (Line 1), 二号线 (Line 2), etc. The phrase 坐几号线 is the standard route question.
• 换乘 — transfer. Chinese metro transfers can involve long walks; 同台换乘 (same-platform transfer) is the dream, 通道换乘 (corridor transfer) is the reality.
• 出站 — exit the station. Each exit is lettered (A口, B口, C口…), and choosing the wrong one can put you on the wrong side of a 8-lane road. Check the exit map before emerging.

坐地铁 is the verb for “take the subway.” 搭地铁 is also common in southern China. Unlike buses, you usually need to go through security (安检 — ānjiǎn) at metro stations; your bag goes through an X-ray machine. The phrase 请安检 is what you will hear.

The metro card is called 地铁卡 or 交通卡, but most people now use their phone’s QR code via Alipay or WeChat. 扫码进站 (scan to enter) is the modern daily ritual.