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.

-29175...
-Arturo, leave her ALONE.
Money Heist Season 1, Episode 10

Wow. I cannot believe we are ALONE
in our own apartment.
The Big Bang Theory Season 10, Episode 4

I need to do this ALONE.
Westworld Season 2, Episode 6

needs a little ALONE
time to decompress.
The Big Bang Theory Season 7, Episode 24

and all he has achieved ALONE.
Vikings Season 1, Episode 8