an undercover agent

• 秘密特工

an undercover agent的用法和样例：

例句

1. Sarah's first assignment as a secret agent was to protect an important witness.
   莎拉作秘密特工的第一个任务是保护一个重要证人。
2. It has also promised a massive security presence at the games, which may include undercover agents dressed as volunteers.
   政府还承诺奥运期间会有大规模现场保安人员，其中可能包括乔装为志愿者的秘密特工。