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.

that pineapples
were once so RARE
The Big Bang Theory Season 12, Episode 3

including the RARE
"DayQuilt" misprint from 1996.
The Big Bang Theory Season 12, Episode 14

which makes you quite a RARE thing
as lords go.
Game of Thrones Season 5, Episode 3

and his study of RARE diseases.
Game of Thrones Season 7, Episode 2

One of my RARE failures,
actually.What went wrong?
The Big Bang Theory Season 12, Episode 23