It ___ be the postman at the door. It’s only six o’clock.

— Do you know where David is ? I couldn’t find him anywhere. — Well. He ______ have gone far –his coat’s still here. 

（山东省淄博市2009学年度高三二摸，35）Zhang Lin was addicted to computer games during his last year in high school , otherwise he         ____________a student of Beijing University .

Kunming is called “Spring City”, but it _____ snow in winter.

She demanded that he _____ the books he borrowed from her.