ace up one's sleeve(或北美 in the hole)

a plan or piece of information kept secret until it becomes necessary to use it

手中握有王牌；有應急妙計

hold all the aces

have all the advantages

占盡優勢

play one's ace

use one's best resource

打出王牌；使出絕招

deciding to play her ace, Emily showed the letter to Vic.

艾米麗決定使出殺手锏，把信拿給維克看。

within an ace of

On the verge of; very near to

差一點，幾乎；非常接近

came within an ace of losing the election.

幾乎失去競選

ace in the hole

A hidden advantage or resource kept in reserve until needed.

錦囊妙計：隱藏的優勢或資源，一直保存到需要時