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.

be the John Dillinger of the Metropolitan
Detention Center. How bad is that?
Breaking Bad Season 5, Episode 15

"I don’t know, the paramedics,
the Metropolitan police...."
Money Heist Season 1, Episode 10

Since you intend to remain
In this lawless METROPOLITAN area...
The Big Bang Theory Season 3, Episode 13