He _____ have fallen asleep last night because he didn’t hear the phone call.

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

Some “healthy” habits, such as shower every day and sitting on the loo, _____ be bad for you.

— Listen! Helen is singing in the classroom.—It _______ be Helen. She has gone to Shanghai.

— I’m afraid you ________play basketball here.— I’m sorry I won’t.