ace in the hole

• n. 最后的王牌；最后王牌

例句

用作名词 (n.)

1. That spare can of gas in the trunk was our ace in the hole.
   后备箱里那罐剩余的汽油是我们最后的王牌。
2. The coach saved his star player for a trump card.
   教练保留他的明星选手，作为他的王牌。