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.

The PLURAL of "coccyx" is "coccyges."
The Big Bang Theory Season 3, Episode 14

The point is women-- PLURAL--
find me appealing.
The Big Bang Theory Season 12, Episode 21

Flaws, Skyler.
Flaws. Plural, not singular.
Breaking Bad Season 3, Episode 12

In fact, that's the bare minimum
to get to the PLURAL "weeks".
The Big Bang Theory Season 11, Episode 14

And yes, that
is the PLURAL.
The Big Bang Theory Season 12, Episode 18