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.

Of course, my GRANDFATHER
died when I was five.
The Big Bang Theory Season 7, Episode 22

That's my GRANDFATHER, Lord Rickard.
Game of Thrones Season 1, Episode 10

do hereby proclaim my GRANDFATHER,
Game of Thrones Season 2, Episode 10

Your GRANDFATHER gave me a necklace
just like this one for my 51 st nameday.
Game of Thrones Season 4, Episode 1

for the funeral
of his GRANDFATHER Lord Hoster Tully.
Game of Thrones Season 3, Episode 3