show one's hand 摊牌

“摊牌”，本意指“把手里所有的牌摆在桌面上（lay one's cards on the table, reveal one's cards）”，后比喻“把事情的有关情况都向对方公开，表明自己的真实意图”，与英文习语“show one's hand”意思相近，表示“to make one's plans, intentions, ideas, or resources known to others, especially those that were previously hidden or kept secret”。

例句：

在商务谈判中，关键是不要马上摊牌，否则你可能会失去最好的交易机会。

In business negotiations, it's important that you don't show your hand right away, or you might risk losing out on the best deal possible.

他们要是不肯摊牌，谈判就不会有进展。

The negotiations will not make progress as long as they refuse to show their hand.