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.

May Euron, your servant,
be born again from the SEA as you were.
Game of Thrones Season 6, Episode 5

Of course, you would have friends
from across the Narrow Sea.
Game of Thrones Season 1, Episode 5

He's found a new way
to navigate the SEA.
Vikings Season 1, Episode 3

The SEA is hundreds of miles away.
Game of Thrones Season 2, Episode 5

Khaleesi of the Great Grass Sea,
Game of Thrones Season 6, Episode 1