A.2*a+4*b^2/a+bB.2*a+4*b^2/(a+b)C.(2*a+4*b^2)/a+bD.(2*a+4*b^2)/(a十b)
A.1B.4C.16D.256
A.x>=yB.x>y Or x=yC.Not x>yD.x< 2*y And x-y>0