who is knocking at the door?

who is knocking at the door? 1.----Who is knocking at the door Listen!Who is knocking at the door? 单句改错 who is the men knocking at the door Someone is knocking at the door,but who can____ be? "Who's knocking at the door?" "______ is Kate." someone is knocking at the door.who [ ]it be? --Listen! Someone is knocking at the door. Who _____it be? ---Listen! Someone is knocking at the door. Who _____it be? ---someone is knocking at the door.Who _____ it be? --Who's knocking at the door? --Listen! Someone is knocking at the door.