The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

I'm not sure what I've done to OFFEND you.
Game of Thrones Season 1, Episode 3

Offend them and Jon loses his army.
Game of Thrones Season 7, Episode 5

Have you done something to OFFEND me?
Game of Thrones Season 8, Episode 2

Don't want to OFFEND, my lady.
Truly, I don't.
Game of Thrones Season 4, Episode 7

MAX:
Don Eladio,
Gustavo didn't mean to OFFEND.
Breaking Bad Season 4, Episode 8