二维数组插入成绩的问题

我在做一维数组插入成绩时的方法放在二维数组放好像是行不通的，代码是一维数组的插入
                        scanf("%d",&i);
            for(j=9;j>=i-1;j--)
            a[j]=a[j-1];
            printf("请输入需要插入的成绩：");
            scanf("%d",&j);
            a[i-1]=j;
            for(j=0;j<=9;j++)
            printf("%d号:%d \n",j+1,a[j]);
可是二维数组的插入怎么想都想不出来，下面的代码是我尝试写的
                                printf("请输入一位成绩:");
                scanf("%d",&k);
                for(i=4;i<10;i++)
                {
                   if(i==4)
                    a[i][i-3]=k;
                for(j=0;j<3;j++)
                    {
                       a[i][j]=t;
                    t=a[i][j+1];
                    a[i][j+1]=a[i][j];
                    }
                }
                for(i=0;i<10;i++)
                  {  for(j=0;j<3;j++)
                       {
                    printf("%4d",a[i][j]);
                       }
                    printf("\n");
                  }