Listen! Is Mary singing in the next room?—No. It _______ be Mary．She has gone to Shanghai for an important meeting.

The university student borrowed some money _____ his friends to start his own business. [ ]

Could you please give this message to Mr. White?— Sorry, I can’t. He doesn’t work here _____.[ ]

As we all know, it’s not polite to keep others _________ for a long time.

The girl is shy . She always feels to speak in front of the class .