—We want someone to design the new art museum for us?—          the young fellow have a try?

The man ______ be my father. My father is much taller.

 ---There is somebody knocking at the door. Who________ it be?---I’m not sure. It ________ be a postman.

— Oh, my cat is really fat.— You __ have given her so much food.

(2012·四川)—Goodbye，John.Come back again sometime.—Sure，________.