We usually work evenings but we left really early. Which underlined adverb can also be used as a noun?

The underlined adverb that can also be used as a noun is early.

Here's why:

* Early as an adverb modifies the verb "left", telling us when they left.

* Early as a noun can refer to a time of day, like "the early morning".

The other word, "evenings", is always a noun.