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.

"Yes, you are a smart
and strong COMPETITOR.
The Big Bang Theory Season 1, Episode 13

Advantage left-side COMPETITOR.
The Big Bang Theory Season 7, Episode 11

They're our number one
COMPETITOR.
The Big Bang Theory Season 12, Episode 17