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.

A HARMLESS courtesy, Your Grace.
Game of Thrones Season 2, Episode 1

I'm just a HARMLESS little girl
with military grade spy equipment.
The Big Bang Theory Season 9, Episode 8

I'm sure it was HARMLESS.
People flirt, no big deal.
The Big Bang Theory Season 9, Episode 14

So don't begrudge your old man
a little HARMLESS fun, huh?
Vikings Season 1, Episode 9

A little, but he's basically HARMLESS.
The Big Bang Theory Season 8, Episode 7