依题意:Card(A)=15 Card(B)=8 Card(C)=14 Card(R)=28Card(A∩B)=3 Card(A∩C)=3 A∩B∩C=空集则Card(B∩C)=Card(A)+Card(B)+Card(C)-Card(A∩B)-Card(A∩C)-Card(R)=15+8+14-3-3-28=3Card(D)=Card(A)-Card(A∩B)-Card(A∩C)=15-3-3=9