123.I met ____ in the street yesterday,who had just come back from Japan.
A.an old friend of my father
B.an old friend of my father's
C.an my father's old friend
D.one of my father's old friend
124.___ is so high that I'm afraid I can't afford it.
A.This computer
B.This computer's price
C.The price of this computer
D.The price of this computer's