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.

What sort of EXPERIMENT
would you propose?
The Big Bang Theory Season 1, Episode 3

Oh, the helmet will sense that
and stop the EXPERIMENT.
The Big Bang Theory Season 12, Episode 5

So are you and Leonard working
on an EXPERIMENT together?
The Big Bang Theory Season 2, Episode 11

You know, if this EXPERIMENT is going to
be valid, I suggest a neutral environment.
The Big Bang Theory Season 10, Episode 4

You said Leonard's EXPERIMENT
was stupid.
The Big Bang Theory Season 3, Episode 10