vb n=0 for i =1 to 3 for j= 4 to i step-1 n=n+1 next j next i print n, i ,j

for j= 4 to i step-1'step这里表示"步长",每次循环减1的递减速度，为从大到小循环。可以理解为"倒叙" n=n+1 next j