my_list = [11, 25, 13, 11, 64, 25, 8, 9]

print("The list is :")
print(my_list)

x, y = 13, 8

x_index = my_list.index(x)

my_result = True
for index, element in enumerate(my_list):
   if element == y and index < x_index:
      my_result = False
      break

if(my_result == True):
   print("所有的y元素在x元素之后出现")
else:
   print("并不是所有的y元素都在x元素之后出现")

The list is :
[11, 25, 13, 11, 64, 25, 8, 9]
所有的y元素在x元素之后出现