You use the "must" in conjunction with another word.

你需要将“must”与其他的词连在一起使用。

Must 课堂 - SpeakingMax英语口语达人

It has been argued, and I think this is a brilliant point, that the most important word in Paradise Lost is or, the conjunction.

或者广受争议的，我个人认为是出色的一个想法，即中最重要的词就是这个连词，或者。

耶鲁公开课 - 弥尔顿课程节选