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》

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。

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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。

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U.S.officials said receiver they arrested Walter Kendall Myers and his wife Gwendolyn after an undercover operation in Washington.

VOA: standard.2009.06.06

IRS-CI started an undercover operation whereby its agents posed as the owners of Continental Indemnity, Ltd.

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Authorities said the undercover operation was started as the result of a tip from a state police informant.

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An ATF official said 55 people were charged with federal and state violations resulting from the seven-month undercover operation.

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