my_list = [4, 45, 75, 46, 66, 77, 48, 99, 10, 40, 5, 8]

print("列表为：")
print(my_list)

a, b = 8, 4

index_a = my_list.index(a)

my_result = [ele for index, ele in enumerate(my_list) if ele != b or (ele == b and index > index_a) ]

print("结果为：")
print(my_result)

列表为：
[4, 45, 75, 46, 66, 77, 48, 99, 10, 40, 5, 8]
结果为：
[45, 75, 46, 66, 77, 48, 99, 10, 40, 5, 8]