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.

Forgive the interruption,
but I believe that we have
an APPOINTMENT.
Westworld Season 2, Episode 2

Never have I ever
canceled a dentist APPOINTMENT.
The Big Bang Theory Season 9, Episode 20

that l am late for an APPOINTMENT.
You're not going anywhere.
Breaking Bad Season 4, Episode 3

Um, I had an APPOINTMENT
The Big Bang Theory Season 12, Episode 23