“ 内鬼” 是贬义词， 英语译为mole，其原意是“鼹鼠”，其比喻意义相当于汉语的“内鬼”。例如：

1. 鼹鼠是一种体小而几乎什么都看不见的动物，身上长着暗灰色或黑色毛皮，在地下打洞，而且大部分时间待在地下。A mole is a small and almost blind animal with dark grey or black fur, that digs tunnels and stays underground most of the time.

2. 内鬼在一个政府部门或组织内工作，秘密地将重要信息传递给敌对国家或组织。A mole works within a governmental department or an organization and secretly passes important information to a rival country or organization.

3. 这家跨国公司经理发现了他的一个竞争对手制订的一项计划，派一名该对手公司招募和培训的内鬼打入他的公司充当会计。The manager of the transnational corporation discovered a plan worked out by one of his rival companies to infiltrate his company with a mole posing as an accountant who had been recruited and trained by his rival company.

“卧底”是中性词，英语译为planted agent。例如：

4. 这名警察在这个贩毒团伙内当了3年卧底，最后帮助警方成功地捣毁贩毒集团，并捉住了毒枭。The policeman served as a planted agent in the drug gang for three years, and finally helped to succeed in destroying the drug gang and capturing its drug king.▲

（本栏目供稿：王逢鑫教授）