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.

So, please, step forward
because you're now a VOLUNTEER.
Money Heist Season 3, Episode 3

- Uh, can I help you?
- Hi, we'd like to VOLUNTEER.
The Big Bang Theory Season 9, Episode 9

The VOLUNTEER.
Money Heist Season 3, Episode 8

Oh, and if I VOLUNTEER to do
track maintenance and paperwork,
The Big Bang Theory Season 10, Episode 15

Ma'am, I'm no VOLUNTEER.
Money Heist Season 3, Episode 3