z*******g
发帖数: 416 | 1 technically wife-husband swap since both couples have kids. | s******r
发帖数: 1137 | | z*******g
发帖数: 416 | 3 It would be zero sum game without ugly spill into the environment.
(m1,f1) +(m2, f2) =(m1, f2) + (m2, f1)
Where kids will still strive in the system. |
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