So like in tennis, usually it's win-lose; it always adds up to zero-zero-sum. But if you're playing doubles, the person on your side of the net, they're in the same boat as you, so you're playing a non-zero-sum game with them.
就像在网球赛中，通常是有输赢的， 比分总是零和的，但是在双打赛中， 你的搭档，与你站在同一战线， 因此你与你的搭档之间，是一种非零和游戏。