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.

I'll definitely live long enough.
Vitamin C.
The Big Bang Theory Season 10, Episode 23

with VITAMIN E.
The Big Bang Theory Season 12, Episode 3

Okay. It's on your head.
You're not supposed to
double up on VITAMIN A.
Breaking Bad Season 2, Episode 8

Yeah, well, chalk it up
to clean living and VITAMIN pills.
Breaking Bad Season 4, Episode 7