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.

- ...is you were a PAIN in the ass.
- The reason I was being a PAIN in the B...
The Big Bang Theory Season 8, Episode 9

Leonard, it is a source of great PAIN
to me and my family...
The Big Bang Theory Season 4, Episode 18

The PAIN was bad.
Game of Thrones Season 4, Episode 7

How is the PAIN, my lord?
Game of Thrones Season 3, Episode 7

(SCREAMING IN PAIN)
Game of Thrones Season 3, Episode 9