帮助Python循环怪异？

for i in range(10):
    i += 1

for i in range(10):
    i = i + 1

my_list = [1, 2, 3, 4]
new_list = [x**2 for x in my_list if x % 2 == 0]

my_list = [1, 2, 3, 4]
new_list = [x**2 for x in my_list if x % 2 == 0]
my_list = [x for x in my_list]

my_list = [1, 2, 3, 4]
my_iter = iter(my_list)
new_list = [next(my_iter) for x in range(len(my_list))]

my_list = [1, 2, 3, 4]
my_iter = iter(my_list)
new_list = [next(my_iter) for x in range(len(my_list))]
my_list = list(my_list)