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.

when he declared his room
a sovereign NATION
The Big Bang Theory Season 12, Episode 10

...and a NATION rallied behind him!
The Big Bang Theory Season 8, Episode 1

The entire NATION dedicated a decade
of effort and treasure...
The Big Bang Theory Season 2, Episode 7

That's of little comfort to a NATION
attempting to scrape burning feces...
The Big Bang Theory Season 4, Episode 7

Those aren't real
Ghost Nation arrows.
Westworld Season 2, Episode 6