Listen.There must be someone_____ in the classroom

Listen.There must be someone_____ in the classroom Listen!There's someone_____(knock)at the door. Listen!Someone_____(cry)over there. He must be in the classroom ,___he? Listen Joan (sing)in the classroom .She often (sing)there. there (be) any computer in the classroom The teacher must _________carefully in class.A. be listen to there must be someone in the room _(be)there HE ( ) in the classroom just now.he ( )be there now Listen!Who____(sing)in the classroom? Listen,someone____(sing)in the classroom. listen to music in the classroom