他在最后一轮谈判中敲定了这笔交易。

He ___clinched the deal in the final round of negotiations.

他紧紧抓住栏杆以免滑倒。

He ___clinched the railing tightly to prevent slipping.

这份合同正式敲定了我们的合作协议。

This contract ___seals our cooperative agreement.