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

 ----_______I come back before 11:00?----No, you________. But you  ________be back later than lunch-time.

—Must I take the medicine every day?— No, you______.

— Can I pay the bill by check? — Sorry, sir. But it's the management rules of our hotel that payment ______be made in cash.

She _____ your birthday party, but she had to look after her mother in hospital．