No one knows until the end of the game whose hidden card is the winner. Often, the ace in the hole wins the game.

直到游戏结束之前，没有人知道谁的底牌会获胜。通常王牌都会得胜。

youdao

He knows something about the boss, which is his ace in the hole.

他对老板有所了解，这是他的王牌。

youdao

AIPAC's ace in the hole is the idea that it represents Jewish interests in a country that is generally philo-Semitic.

在一个普遍“亲犹”的国家中代表犹太人的利益，这也许是AIPAC手中最大的王牌。

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Often,the ace in the hole wins the game.

VOA: special.2009.11.22

For example, you hear the expression, ace in the hole, used by many people who would never think of going near a poker table.

VOA: special.2009.11.22

An ace in the hole is an argument, plan or thing kept hidden until needed.

VOA: special.2009.11.22

But the reason why so many of these mortgage companies were making loans that banks couldn't make is because they had an ace in the hole, and their ace in the hole was Wall Street.

NPR: Will Interest-Rate Cut Really Help?

"It's clear they feel that the one ace in the hole that they still hold is national security and fighting terrorism, " VandeHei says.

NPR: Editor: Republicans in Worst Shape Since Watergate

Like any good gambler though, opponents of this critical resource development have an ace in the hole.

FORBES: EPA is Obama's Offshore Drilling Ace in the Hole