Cách sử dụng
When someone says they "know somebody by sight," it means they have seen and recognize that person, but they may not necessarily know their name or any personal details about them. For example, if someone says they "know the janitor by sight," they mean they have seen the janitor around, but they may not know their name or where they are from. This expression is commonly used in informal situations, such as when describing someone you have seen around but do not know well.