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.

They DEMAND to see you, Your Grace.
Game of Thrones Season 6, Episode 8

Now I DEMAND a champion.
I have that right, same as you.
Game of Thrones Season 1, Episode 6

If you DEMAND blind allegiance,
Game of Thrones Season 7, Episode 2

Well, who am I to fly in the face
of public DEMAND, right?
Breaking Bad Season 5, Episode 8

I DEMAND entry.
Game of Thrones Season 6, Episode 8