Eggs in western countries are often sold by _____.

A．a dozen

B．the dozen

C．dozens

D．dozen

-(56)题基于以下叙述：有关系模式P(A,B,C,D,E,F,G,H,I,J)，根据语义有如下函数依赖集：F={ABD→E,AB→G,B→F,C→J,C→I,G→H}(54) 关系模式P的码是

A．(A,

B．(A,B,

C．(A,

D．(A,B,C,D）