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.

But neither of those is a COGENT argument
for titanium over nanotubes.
The Big Bang Theory Season 1, Episode 12

Those are very COGENT
and reasonable conditions.
The Big Bang Theory Season 3, Episode 4