如何以不同的顺序输出"for“循环中的不同变量？

for i in range(5):
    print(i)

for j in range(5):
    print(j)

0
1
2
3
4
0
1
2
3
4

for i in range(5):
    for j in range(5):
        print(i, j)

0 0
0 1
0 2
0 3
0 4
1 0
1 1
1 2
1 3
1 4
2 0
2 1
2 2
2 3
2 4
3 0
3 1
3 2
3 3
3 4
4 0
4 1
4 2
4 3
4 4

variables = ['a', 'b', 'c', 'd']

for var in variables:
    print(var)

a
b
c
d