求volume(1,1)+volume(2,1)+...+volume(20,1)吗? 加如下的语句在主程序中就可以了,用求和的语句: @for(supplyment(I): s=@sum(receiver(J)|J#le#2:volume(I,J))); 即修改后的程序是 sets: supplyment/s1..s20/: supply; receiver/r...