I'm always wondering this question: what benefits can people get from using different forms of words in different contexts?
We say "he learns English" instead of "he learn English" but doesn't the pronoun "he" already indicate the sentence is in 3rd person?
We say "yesterday he drank too much beer" instead of "yesterday he drink too much beer" but doesn't the word "yesterday" already indicate the action happened in the past?
We say "he is going to read these 3 books during the holiday" instead of "he is going to read these 3 book during the holiday" but doesn't the number "3" already indicate how many books there are?
How is having various word forms advantageous in languages like English?