an ace up your sleeve
US /ən eɪs ʌp jʊər sliːv/
UK /ən eɪs ʌp jʊər sliːv/
1.
一张王牌, 秘密优势
a secret advantage or resource that can be used when needed
:
•
The politician had an ace up his sleeve for the debate.
这位政客在辩论中留有一张王牌。
•
She always keeps an ace up her sleeve for negotiations.
她总是在谈判中留有一张王牌。