输出“12 9 6 3 ”，下列程序不正确的是？（ ）
for i in range(12,0,-3):
print(i,end=" ")
for i in range(12,3,-3):
for i in range(4,0,-1):
print(3*i,end=" ")
for i in range(5,1,-1):
print(3*(i-1),end=" ")