4 sentences

1. 你现在是他的见证人了。

   nǐ xiàn​zài shì tā de jiàn​zhèng​rén le.

   You're his witness now.

   Source: OpenSubtitles

2. 你的见证人呢？

   nǐ de jiàn​zhèng​rén ne?

   Where's your witness?

   Source: OpenSubtitles

3. 警方正在寻找这起事故的现场见证人。

   jǐng​fāng zhèng​zài xún​zhǎo zhè qǐ shì​gù de xiàn​chǎng jiàn​zhèng​rén.

   The police are looking for eyewitnesses to the accident.

   Source: Dong Chinese Dictionary

4. 他在见证人的陪同下签署了这份重要的协议。

   tā zài jiàn​zhèng​rén de péi​tóng xià qiān​shǔ le zhè fèn zhòng​yào de xié​yì.

   He signed this important agreement in the presence of a witness.

   Source: Dong Chinese Dictionary