--- Do we have to hand in our research reports this afternoon, Professor Smith?--- Yes, you _______ . I will be waiting to check them all the afternoon.

 －Must I go and get some water now?   －No, you __________.

—Must I finish the homework tonight?—No, you        .You can finish it tomorrow.

She was greatly shocked at the scene before her eyes. Never did she expect that the local conditions ______ be so awful.

— There’s somebody at the door. Who ______ it be? Is it the postman ?—No, it ______ be him. It’s just seven o’clock. It’s too early.