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.

Sheldon took it.
We're kind of MOLE buddies.
The Big Bang Theory Season 11, Episode 11

Oh... that's
a MOLE on my back.
The Big Bang Theory Season 11, Episode 11

You measured the diameter of
his suspicious MOLE yesterday.
The Big Bang Theory Season 7, Episode 6

"When there's hair growing out of it,
that's a MOLE."
The Big Bang Theory Season 10, Episode 17

Do I have to remind you
that there’s a MOLE?
Money Heist Season 1, Episode 10