锁门

Using it is incredibly straightforward. You can use it as a standalone command. You can also add it to a sequence of actions. For example, 记得锁门 means 'remember to lock the door.' If you want to say you have already done it, add 了 (le) at the end. 我锁门了 means 'I locked the door.' It is very flexible and fits into most sentence structures easily.

Use this when you are leaving your apartment. Use it when you are the last one to leave the office. It is perfect for checking in with roommates or family members. You might text your spouse: 你锁门了吗？ (Did you lock the door?). It is also used in hotels or public restrooms. Basically, anywhere with a door and a lock is fair game.

Do not use 锁门 if you are talking about locking a digital file. For computers or phones, use 锁屏 (suǒ píng) for 'lock screen.' Also, do not use it for 'locking' a deal or a contract. That requires more formal business vocabulary. This phrase is strictly for physical doors. If you are locking a drawer, you would just say 锁抽屉 (suǒ chōutì).

In modern Chinese cities, most people live in high-rise apartments. These doors often have high-tech smart locks or heavy-duty deadbolts. The phrase 锁门 carries a sense of safety and privacy. In older 'hutong' neighborhoods, people might not have locked their doors during the day. Today, however, locking up is a universal habit. There is even a common 'OCD' joke in China. People often walk down three flights of stairs, then wonder if they actually locked the door.

If you want to be more specific, you can use 把门锁上 (bǎ mén suǒ shàng). This emphasizes the completion of the action. You might also hear 反锁 (fǎn suǒ). This means to deadbolt the door from the inside for extra security. If you forget your keys, you might say 没锁门 (méi suǒ mén), meaning you left it unlocked. It is a simple phrase with many small, useful branches.