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.

there is no WEAKNESS left in them.
Game of Thrones Season 3, Episode 1

I'm the WEAKNESS?
Game of Thrones Season 2, Episode 3

How is being a WEAKNESS a compliment?
Game of Thrones Season 2, Episode 3

No, my lord. That's not my WEAKNESS.
Game of Thrones Season 3, Episode 7

If the other houses
sense WEAKNESS on his part,
Game of Thrones Season 6, Episode 9