1·Officers had tailed the gang during a major undercover operation.
警方在一次重大的秘密行动中跟踪过这个团伙。
—— 《柯林斯英汉双解大词典》
2·1: Surprises: Andy and Nick go missing during an undercover operation in the Season 4 premiere.
第1集：惊喜：安迪和尼克失踪在一个秘密行动在本赛季4首映。
3·3: Eye of the Storm: An undercover operation threatens to expose a secret that could ruin Inspector Briggs.
第3集：风暴之眼：一个秘密行动威胁要揭露一个秘密，这可能会毁掉布里格斯。
4·In every undercover operation, there is a tipping point, a moment when the bad guys move from suspicion to trust.
在每次卧底行动中，都有临界点，一个坏人由怀疑到信任的时刻。
5·The men had been recovering at a San Antonio, Texas hospital since being rescued in an undercover operation last week.
这几人上周被秘密救出后，被送往德克萨斯州圣安东尼奥的一家医院，目前正在恢复中。
6·In an undercover operation the newspaper's reporter approached 6 current or former FIFA officials all of whom suggested "paying huge bribes to FIFA executive committee members."
该报记者称，在“钓鱼行动”中，他们所接触的6名前任或现任世界杯官员均暗示“世界杯申办权须贿赂执委会成员才能换得。”
7·The operation followed months of undercover police work that gathered evidence of an extraordinarily lucrative empire.
经过数月的秘密工作，收集了这个非常有利可图的团伙的证据之后，警察展开了这次行动。