—I was asked to attend the meeting before eight.—Oh, you________. I'm sorry for not telling you that we have changed the plan.

You'd better not ride the bicycle on snowy days; you ______ fall．

--- Whose comic book is it?  --- It ________ be Daniel’s. He often shares his comic books with his friends.

 —___________ he have to wear his school uniform every day?—No, he ______________.

-Listen! Is Mary playing the piano in the room?  --No. It ________ be Mary. She has gone to Hong Kong.