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.

Until I can transfer my intellect
to a more durable container...
The Big Bang Theory Season 4, Episode 2

It was. Until I found out you never told her
we're not gonna live with her.
The Big Bang Theory Season 6, Episode 1

and that's what I'll do
UNTIL he tells me otherwise.
Game of Thrones Season 1, Episode 4

and lock you in a bedchamber
UNTIL you remembered that you were brothers.
Game of Thrones Season 2, Episode 4

None of this means a thing
UNTIL we take King's Landing.
Game of Thrones Season 8, Episode 4