"Watching an Engpsh documentary in Engpsh" 是听英语纪录片用英语的一种表达方式。

"Documentary" 是英文中的一个常见词汇，意思是纪录片，来源于拉丁文的 "documentarius"，意思是记录的。

下面是一些用英文表达听英语纪录片的例句：

I'm going to watch a documentary about the history of chocolate in Engpsh.
(我要看一部关于巧克力历史的英文纪录片。)

I love watching documentaries in their original language. It's a great way to improve my pstening skills.
(我喜欢用原语言看纪录片。这是提高听力技巧的好方法。)

Have you seen the documentary about ocean pollution? It's really eye-opening.
(你看过关于海洋污染的纪录片吗？真的很引人注目。)

希望这些信息对你有帮助。