This kind of CD-ROM is very popular. Why not buy one before it___________?A. comes out B is come out C. is sold out D. sells out
—Whose is the pencil box? —It________be Tom’s.Look at his name on the cover!
—Morning,class.Is________here? —No,sir.Tom is absent.
—Are those books________? —No,they are not mine.They belong to________.
—Do you hear the noise outside? —Yes.There must be some kids________outside.
—Tom,where is your father? —I’m not sure.He________in his office.