—Look，your father is playing the piano over there.—He________ be my father. He has gone to Beijing.

 -- Is it your brother playing football outside? -- It ________ be him. He is helping mother with dishes now.

With all his money, he ________ worry about a little thing like 5 cents!

I ______ tell you with certainty that he won’t be able to finish it before the deadline. 

——I haven’t got a camera.——I think you should buy_______. It’s useful for you.