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.

{\i1}there are the secrets{\i0}
{\i1}from the Ministry of the Interior, {\i0}
Money Heist Season 3, Episode 5

Interior angle of a hexagon
is 120 degrees.
The Big Bang Theory Season 3, Episode 14

from the entire
INTERIOR of the body,
Vikings Season 1, Episode 7

Among them, the Minister of the Interior,
the State Secretary of Foreign Affairs
Money Heist Season 3, Episode 5

{\i1}The Minister of the Interior,{\i0}
{\i1}the Chief of the Defense Staff,{\i0}
Money Heist Season 3, Episode 5