Why not? It's my best card.

为什么 这是我的杀手锏。

I knew he simply couldn't have the best cards all the time.

我知道他不可能一直拥有最好的牌。

After a long and desperate struggle, the American Minister had trumped their best card and won the game.

经过长时间的殊死搏斗， 美国公使打出了他们最好的牌， 赢得了比赛。