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.

Your hands registered
as LETHAL weapons?
Breaking Bad Season 4, Episode 6

...it is poisonous in its raw form
and LETHAL if prepared improperly.
The Big Bang Theory Season 2, Episode 13

from being a LETHAL disease
for all those who suffer it
Money Heist Season 1, Episode 9

I didn't get you started
on Lethal Weapon.
The Big Bang Theory Season 12, Episode 8

It's called Lethal Weapon,
The Big Bang Theory Season 12, Episode 8