注意for循环对应的层次，print的缩进位置不一样，对应的不一样，你这是对应的for循环，那么每循环一次就会打印一次，Python对缩进很严格

L = [75, 92, 59, 68, 99];

sum = 0;

i = len(L);

for ch in L:

    sum += ch;

print(sum/i);

# Enter a code

s1='ABC'

s2='123'

s3='xyz'

sout=''

for c1 in s1:

    for c2 in s2:

        for c3 in s3:

            sout= sout +c1+c2+c3+'\n'

print(sout)