What does a verb modifiy?

Answer 1

Verbs don't modify anything. They describe the action or state-of-being of the subject of the sentence. They can, however, be transformed into participles, which act as adjectives modifying nouns.

infinitive form of verb >> participle form

to write >> written

"He wrote a book." <= used as a verb

"the written word" <= used as an adjective

to walk >> walked

"He walked the dog." <= used as verb (past tense)

"The dog, when walked, did not poop in the house." <= used as participle, meaning the "dog, when taken for a walk". If this were a verb, it would imply that the dog was walked on, like you would say "He walked the tightrope." meaning "he walked on the tightrope."