What are the concrete and abstract nouns in this sentence Mr Fernandez is teaching us about great world leaders?

Here's a breakdown of the concrete and abstract nouns in the sentence:

Concrete Nouns:

* Mr. Fernandez: A specific person.

* us: Refers to a specific group of people.

* world: Refers to the physical planet we live on.

* leaders: People who hold positions of authority.

Abstract Nouns:

* teaching: The act of instructing.

* greatness: A quality or characteristic of being excellent or impressive.

* leaders: While the word "leaders" can be concrete, it's used here to represent the abstract concept of leadership.

Let me know if you'd like more examples of concrete and abstract nouns!