undercover

1. ADJ Undercover work involves secretly obtaining information for the government or the police. 秘密的

...an undercover operation designed to catch drug smugglers. …一次爲抓捕毒品走私販而策劃的秘密行動。

...undercover FBI agents. …聯邦調查侷的密探。

2. ADV Undercover is also an adverb. 秘密地[ADV after v]

Swanson persuaded Hubley to work undercover to capture the killer. 斯旺森說服了赫佈利秘密工作以捕獲兇手。