该团队的主要任务是确保在夜幕降临前占领这个偏远的前哨站。

The team's primary ___mission was to secure the remote outpost before nightfall.

她被派去执行一项外交任务，以谈判一项新的贸易协定。

She was sent on a diplomatic ___mission to negotiate a new trade agreement.

整个行动的成功与否取决于这次秘密任务能否不被发现。

The success of the entire operation depended on the covert ___mission going undetected.