Cách sử dụng
"Come in" is an expression commonly used to invite someone into a room or building. It can be used when someone knocks on the door or when you see someone outside waiting to enter. Saying "come in" is a polite way to ask the person to enter and join you. It is also used as a greeting when someone arrives at a place like a shop or a store. For example, a shopkeeper might say "hello, come in" to a customer who just walked into the store.