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.

...based on the number of mailboxes and
given typical urban population DENSITY...
The Big Bang Theory Season 2, Episode 15

That is true.
I have a higher than normal body DENSITY.
The Big Bang Theory Season 6, Episode 4