try学英语每日一词（每日英语aceup）

ace up (one's) sleeve 秘密王牌，锦囊妙计

A secret plan, idea, or advantage that can be utilized if and when it is required.

My stamina is the ace up my sleeve for this race—the other runners don't stand a chance!

我的毅力是我赢得这场比赛的王牌-其他选手根本没有机会。

The defense attorney waited for just the right time to play the ace up her sleeve—

a new eye-witness.

辩护律师等着在恰当的时间亮出它的杀手锏：一个新的目击证人。

She's keeping all the details of their unscrupulous business practices as an ace in her

sleeve should they ever try to fire her.

她把他们不择手段的商业行为的所有细节都掌握在自己手里，以防他们想要解雇自己。