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.

...and we might have been
followed here by a DRONE.
The Big Bang Theory Season 6, Episode 23

Colonel,
a DRONE has located the Professor.
Money Heist Season 3, Episode 7

No, it's more of a relentless,
narcissistic DRONE.
The Big Bang Theory Season 2, Episode 10

Our D.P. John Grillo wanted
to feel the DRONE presence.
Westworld Season 3, Episode 8

Just flip the switch until the lights
on the DRONE change to solid yellow.
The Big Bang Theory Season 8, Episode 22