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.

She has committed the acts
of FALSEHOOD and fornication.
Game of Thrones Season 5, Episode 10

There's a great deal of FALSEHOOD
in Cersei. You know that.
Game of Thrones Season 6, Episode 3

It's a FALSEHOOD. I swear it.
Game of Thrones Season 2, Episode 3