---Fifty dollars for such a T-shirt! You _______ be joking!---I’m serious．It’s made of silk.

 She is a quiet girl at school，but sometimes she _____ be very naughty.

You           be hungry after the long walk．Help yourself to some cakes．

Please remind your grandpa to take medicine on time, for a man of his age ____be very forgetful．

John, you          play with the knife, or you          hurt yourself.