an ace in the hole
成語所屬單字hole
an ace in the hole — 慣用語
1. A secret advantage that you keep ready to use when needed.
1.慣用語
釋義
祕密王牌
A secret advantage that you keep ready to use when needed.
例句
Maya kept her coding skills as an ace in the hole.
Did Brian have an ace in the hole for the negotiation?