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.

Not necessarily. I'm often surprised
by my LACK of familiarity with Leonard.
The Big Bang Theory Season 1, Episode 17

Because it's not our territory?
Because we LACK initiative.
Breaking Bad Season 2, Episode 7

that could reconcile the LACK
of observation of supersymmetry
The Big Bang Theory Season 12, Episode 5

But not for LACK of trying.
Breaking Bad Season 3, Episode 8

Whoever's her partner will be hamstrung
by her LACK of experience, not to mention...
The Big Bang Theory Season 1, Episode 7