—Must I finish my homework at school?— No, you_____. you can do it at home

It was fine yesterday so I ______ the trouble to carry my raincoat with me.

Looking after very young children _____ be very annoying sometimes, but you’ll get used to it after a while.

— Professor Smith, some students want to have a talk with you. ___ they wait here or outside?— Show them in now, please.

— Listen! Helen is singing in the classroom.—It _______ be Helen. She has gone to Shanghai.