Question

fix the one word that is used incorrectly.
when president franklin roosevelt gave his famous fireside chats, he
would set behind a desk covered in microphones rather than beside a
fireplace.

Explanation:

The incorrect word "set" is a transitive verb that requires an object. The correct intransitive verb to describe positioning oneself is "sit".

Answer:

Replace "set" with "sit". The corrected sentence is: When President Franklin Roosevelt gave his famous fireside chats, he would sit behind a desk covered in microphones rather than beside a fireplace.