已知0已知0
已知000,loga(y)>0 1=loga(x)*loga(y)<={[loga(x)+loga(y)]/2}^2=[loga(xy)/2]^2 loga(xy)/2>=1,loga(xy)>=2,0注意到取得等号条件是x=y,但是x<y所以0没有最大,最小值,选B