4 sentences

1. 我是一名卧底警察。

   wǒ shì yī míng wò​dǐ jǐng​chá.

   I'm an undercover cop.

   Source: OpenSubtitles

2. 我是《芝加哥太阳报》的卧底记者。

   wǒ shì《 Zhī​jiā​gē Tài​yáng Bào》 de wò​dǐ jì​zhě.

   I'm an undercover reporter for the Chicago Sun-Times.

   Source: OpenSubtitles

3. 这名卧底成功潜入帮派，获取了核心犯罪证据。

   zhè míng wò​dǐ chéng​gōng qián​rù bāng​pài, huò​qǔ le hé​xīn fàn​zuì zhèng​jù.

   The undercover agent successfully infiltrated the gang and obtained key criminal evidence.

   Source: Dong Chinese Dictionary

4. 警察派他去那个犯罪团伙卧底。

   jǐng​chá pài tā qù nà gè fàn​zuì tuán​huǒ wò​dǐ.

   The police sent him to go undercover in that criminal gang.

   Source: Dong Chinese Dictionary