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.

A VALID point, but unoriginal. B-minus.
The Big Bang Theory Season 8, Episode 2

That's actually a VALID example.
The Big Bang Theory Season 8, Episode 21

I think what you're feeling is VALID
and maybe later today...
The Big Bang Theory Season 1, Episode 2

That was a VALID hypo...?
What is happening to you?
The Big Bang Theory Season 1, Episode 1

That is a VALID point.
The Big Bang Theory Season 10, Episode 19