Question 1038624
I'd pick the sets of 2 that aren't used.
12---34567
13---24567
14--23567
15--23467
16--23457
17--23456
23--14567
24--13567
25--13467
26--13457
27--13456
34--12567
35--12467
36--12457
37--12456
45--12367
46--12357
47--12356
56--12347
57--12346
67--12345