---I stayed at a hotel while in New York.---Oh, did you? You ________ with Barbara.

— What does the sign over there say?— No person ______ enter the area without the official permission.

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

It is usually warm in my hometown in March, but it _____ be rather cold sometimes.

 —Whose book is this? —It _____ be Mary’s. Mo Yan is her favorite author. —No, it ____ be hers, she never brings novels to school.