Here's why:
* Common Noun: It refers to a general concept, not a specific person, place, or thing.
* Concrete Noun: It refers to something that can be perceived by the senses (we can experience evening through darkness, cooler temperatures, etc.).
It's also worth noting that "evening" can sometimes act as an abstract noun when it's used metaphorically. For example: "The evening of his life was filled with peace." In this case, "evening" represents the later stages of a person's life.