english
1
general::
Phrase(s): Who’s there? [and] Who is it? a question asking who is on the other side of a door or concealed in some other place. • Hearing a noise, Tom called out in the darkness, "Who’s there?" • Hearing a knock on the door, Mary went to the door and said, "Who is it?"
McGrawhill's American Idioms And Phrasal Verbs