报案

You usually use it as a verb. You can say 我要报案 (I want to report a case). You don't need a complex object after it. If you lost your phone or someone stole your bag, this is your go-to word. It sounds serious but necessary. It is like hitting the 'official' button on a bad situation.

Use it when you are at a police station or calling 110. It is perfect for theft, accidents, or witnessing something illegal. If you are talking to a friend about a crime, you use it too. For example, 'Did you 报案 yet?' It shows you are taking action. It is the language of responsibility in a crisis.

Do not use it for small personal arguments. If your roommate ate your leftovers, don't say you will 报案. That is way too dramatic! Also, don't use it for medical emergencies. For those, you call an ambulance, you don't 'report a case.' Keep it strictly for legal or criminal matters.

In China, the emergency number is 110. When you call, the first thing they might ask is if you want to 报案. There is a strong emphasis on 'filing the record' (备案). People are generally encouraged to 报案 even for small thefts. This helps the police track crime patterns in the neighborhood. It is seen as a civic duty.

You might hear 报警 (bàojǐng) which means 'call the police.' While 报警 is the act of calling, 报案 is the act of filing the report. They are often used together. You call the police (报警) so that you can report the case (报案). Think of 报警 as the action and 报案 as the official procedure.