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；有应急妙计

hold all the aces

have all the advantages

占尽优势

play one's ace

use one's best resource

打出王牌；使出绝招

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

艾米丽决定使出杀手锏，把信拿给维克看。

within an ace of

On the verge of; very near to

差一点，几乎；非常接近

came within an ace of losing the election.

几乎失去竞选

ace in the hole

A hidden advantage or resource kept in reserve until needed.

锦囊妙计：隐藏的优势或资源，一直保存到需要时