Which of the following is an aphorism?
a. franklin was a creative force in america
b. too many cooks spoil the broth
c. it was my sincere desire to go back home
d. people appreciate random acts of kindness

the answer is:

when will (v) the books (n) be (v) due?

nouns refer to people (other than pronouns), places and things, whereas verbs describe actions and are usually part of the predicate of a sentence. finally, pronouns can work as nouns and identify the participants in speech.

in the example sentence, "will" is a verb part or auxiliary verb, "be" is an infinitive verb and "books" is a plural noun.