— Look, it _____ be Jack who is at the gate of the library.

Look!The man at the gate _____ be our headmaster .He is alwa ---someone is knocking at the door.Who _____ it be? —There is somebady at the door.Who _____ it be? Who is the person is standing at the gate of Beijing Tourism Who is the person -------- is standing at the gate? Who is the person ____ is standing at the gate? 6.There is someone knocking at the door,who _____ it be? Someone is knocking at the door.Who it be?— It be Tom.He is Look at the clock! It is time _____ home. look,jack!who _____(sing)in the next room? —Is Jack in the library? jack is the only one of the students who was praised at the