21．—What does the sign over there read?

—No person _______ smoke or carry a lighted cigarette, cigar or pipe in this area．

A．must  B．may   C．shall   D．will

22．Finding his cell phone stolen on the bus, _________．

A．the bus driver was asked to help         

B．the bus was searched thoroughly

C．it was looked for everywhere           

D．Steve hurried to a policeman for help