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.

That'd be a good SLOGAN
for a condom company.
The Big Bang Theory Season 12, Episode 7

And my SLOGAN was, "A line
this straight is a line that's great."
The Big Bang Theory Season 9, Episode 23

Yeah, their SLOGAN is,
The Big Bang Theory Season 10, Episode 16

It's like the SLOGAN says:
The Big Bang Theory Season 3, Episode 7