—Why don’t you go home now ?—OK. Let’s go.
—Look,your father is playing the piano over there.—He________ be my father. He has gone to Beijing.
Thank you for giving me __________.
Chinese is used ______ the largest number of people in the world.
The woman has something wrong with her eyes and has to have them _________.
Our friends were _______ busy ______ with each other _______the time.