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.

we start FILLING in the gaps, I'll have
him in lockup before the sun goes down.
Breaking Bad Season 5, Episode 10

I'm FILLING in for her husband
who's recovering
The Big Bang Theory Season 7, Episode 11

Yeah. I'm standing there FILLING up
like I've done a thousand times
Breaking Bad Season 5, Episode 12

They're just FILLING
the furnace now.
Westworld Season 2, Episode 6

Sometimes he finds that FILLING,
other times he doesn't.
The Big Bang Theory Season 1, Episode 3