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.

Unfortunately, we weren't able
to CONVINCE him to go to rehab.
The Big Bang Theory Season 1, Episode 10

would CONVINCE any Spaniard
to sell their mother.
Money Heist Season 3, Episode 7

and CONVINCE whoever it is
that we are closed
Money Heist Season 1, Episode 1

Only a king can CONVINCE her
to help us.
Game of Thrones Season 7, Episode 2

And you need to CONVINCE
the one with the dragons,
Game of Thrones Season 7, Episode 5