my_list = [5, 7, 2, 7, 2, 4, 9, 8, 8]

print("列表是：")
print(my_list)

search_set = {6, 2, 8}

my_result = []
for element in my_list:

   if element in search_set:
      my_result.append(element)

print("结果是：")
print(my_result)

The list is :
[5, 7, 2, 7, 2, 4, 9, 8, 8]
The result is :
[2, 2, 8, 8]