=if(and(a1<>"",b1<>"",d1<>"",e1<>""),if(and(a1=d1,b1=e1),c1=f1,""),"有单元格为空")
c1 写公式=if(and(a1=d1,b1=e1),f1,"")
=if(AND(A1=D1,B1=E1),C1=F1,)