What is the pattern behind this sequence? How might it continue?
Roland is on the right track, but it's
To go through what we have:
Ought/Naught/Nought (depending on your dialect) -> bought and sold (believe it or not, I thought of it myself and then saw Roland and Echo say it in comments)
One -> sun and moon,
Two -> true and false,
Three -> tea and coffee,
Four -> war and peace,
Five -> live and neutral (terms from AC current),
Six -> sticks and stones,
Seven -> heaven and hell,
Eight -> state and private (like colleges -- thanks Bailey M from comments),
Nine -> line and plane
It might continue with
Ten -> pencil (pen and pencil)
Eleven -> Kell (Kevin and Kell)
This is almost certainly wrong, but my guess at the riddle's format might not be.
Each word in the sequence brings common idioms to mind, as well as opposite/counterparts, like Moon and Sun, True and False, etc. The pattern involves idioms with the words in the sequence as well as with their counterparts.
Blood Moon -- True Blood -- True/False
False Start -- Starting Tee -- Tee(Tea)/Coffee
Cold Coffee -- Cold War -- War/Peace
To come in Peace -- To be in Charge -- Charge(d)/Neutral
I'll work on some more if this isn't absolutely wrong, but it feels really forced on my end. My next pairings were going to be:
Train/Plane (vehicles) or Line/Plane (geometry)