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.

Yeah, I am.
I'm a PHARMACEUTICAL sales rep.
The Big Bang Theory Season 12, Episode 6

Perfect for a PHARMACEUTICAL plant
or microchip factory
Breaking Bad Season 4, Episode 7

a successful PHARMACEUTICAL rep.
The Big Bang Theory Season 10, Episode 11

In the PHARMACEUTICAL business,
we have a saying:
The Big Bang Theory Season 7, Episode 6

Before I did PHARMACEUTICAL sales,
I was an actress.
The Big Bang Theory Season 9, Episode 12