---- __________ you say goodbye so soon? ---- I’m sorry. My mother is expecting me at home. 

 --What kind of apartment do you want to rent? A large one, Mr. Smith? --Er, it ________ be a large one, as my family is not large.

It ____ be our headmaster. He has gone to Beijing.

-- A medical team was sent to Japan by air five hours ago. ---So they_____ have arrived by now. The flight usually takes four hours or so.

--- Do you mind if I smoke here in the living room? --- Well, if you ___.  But I’d rather you didn’t.