If you _______ carry with you the belief that all you do is right, it’s none of my business.   

— Wow! You look different! You            wear glasses.— Yes, I did. But now I am wearing contact lenses(隐形眼镜).

—Tom graduated from college at a very young age.—Oh,he__________have been a very smart boy then.

--- Listen! David is talking happily with his mother in the next room.　--- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.

—There is a pen on the ground. Is it Li Long’s?—It         Li Long’s. He went to Beijing many days ago.