list内含有元组或字典

a=[("","",""),("","","")]
for k,v,i in a:
    print(k,v,i)
结果：
1 21 12
2 31 32

list里含元组，可以用这种遍历输出挨个元素

但list里含字典时，这样就只能输出keys了

b=[{"1":12,"2":1,"3":11},{"4":2,"5":21,"6":22}]
for k,v,i in b:
    print(k,v,i)
 结果：
1 2 3
4 5 6

for i in b:
    for k,v in i.items():
        print(k,v)
结果：

1 12
2 1
3 11
4 2
5 21
6 22