WORD USAGE AND WORD RELATIONSHIPS
Many words have relationships. Some even get married. A great deal of bitterness can result when words get divorced. Custody battles over the letter E have led to some very embarrassing pronounciations.
AGREEMENT OF SUBJECT AND VERB
This only happens when the agreement is beneficial to both parties. Subjects always seem to think of themselves as the center of the universe which pisses off whatever verbs happen to be in the same room.
Forget about it. It's way too confusing and no one really cares anyway.
AGREEMENT OF PRONOUN WITH ITS ANTECEDENT
Actually, pronouns and antecedents never agree on anything. Many a Thanksgiving dinner has been ruined over the years with their silly squabbling.
Some words are quite easy to confuse. The word "tephrosis" was once so confused that it thought it was a dalmation puppy in a Disney movie.