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.

And did they ever HARM you?
Game of Thrones Season 6, Episode 2

What HARM could Lyanna Stark's ghost
do to either of us
Game of Thrones Season 1, Episode 5

I promise you no HARM
will come to your daughter.
Vikings Season 1, Episode 2

- What is the HARM if I audition?
- Well, what if you get it?
The Big Bang Theory Season 8, Episode 20

We mean no HARM.
Westworld Season 2, Episode 5