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.

Eighteen kilometers per hour.
Money Heist Season 3, Episode 8

--EIGHTEEN, 19 and 20.
Breaking Bad Season 5, Episode 11

If you would just let me.
Eighteen months.
Breaking Bad Season 2, Episode 12

Eighteen years ago,
I sent the FBI Crime Lab samples...
The Big Bang Theory Season 4, Episode 7

Eighteen parts per million.
The Big Bang Theory Season 8, Episode 9