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.

Had this firearm INSTRUCTOR
who was...
Breaking Bad Season 2, Episode 10

You know, when
my yoga INSTRUCTOR was pregnant,
The Big Bang Theory Season 11, Episode 16

Oh, I know a CPR INSTRUCTOR
who'll come to the house.
The Big Bang Theory Season 10, Episode 10