covert

政府正在进行一项秘密调查。

The government is conducting a ___covert investigation.

这名员工通过公园里的秘密交接点向竞争对手公司传递了隐秘信息。

The employee passed ___covert messages to a rival company through dead drops in the park.

他们在董事会期间悄悄交换了微笑，小心不让主席发现。

They exchanged ___covert smiles during the board meeting, careful not to let the chairman notice.