There are so many contradictions and loony, often-broken rules in the English language, I can’t imagine having to learn it as a second language. Here are some brief examples.
Using “ir” to make words opposite: responsible – irresponsible refutable – irrefutable rational – irrational
Using “ir” doesn’t change the word’s meaning: regardless – irregardless
Removing “ir” does not create a real word: ironical – ronical? irrigate – rigate? irritable – ritable?
Valuable information, right? Or is it invaluable?