List all the abstract nouns in this sentence: in the odyssey by homer, the protagonist odysseus displays great cleverness and courage when he blinds the one-eyed giant polyphemus.

The abstract nouns in the sentence are cleverness and courage.

Explanation:

These two nouns refer to qualities, and these, beside emotions, feelings, states, concepts, ideas and events, are part of the abstract nouns. This type of nouns are related to elements that you can not detect by your five physical senses (you can not taste them, see them, smell them, hear them, and touch them), in opposition to the concrete nouns.

Everything that abstract nouns name it only exist in the mind, and is linked by  the particular point of view of each person.

i would say the correct answer is not concrete.