>>> [' '.join(i) for i in zip(s,s[1:])]
['A B', 'B C', 'C D', 'D E', 'E F', 'F G']
>>> for i in [' '.join(i) for i in zip(s,s[1:])]:
...  print i
...
A B
B C
C D
D E
E F
F G
>>>