既能删除列表中的重复元素，又能保留原来的顺序

l1 = [1, 1, 2, 2, 3, 3, 3, 3, 6, 6, 5, 5, 2, 2]
for i in range(len(l1)-1, 0, -1):
    if l1.count(l1[i]) > 1:
        l1.pop(i)
print(l1)