I'll give you a hint what is the question you just asked? if you don't get that then what is the definition of flue?
flue you
At the beginning of fall, before you build a fire in your fireplace make sure to open the chimney's flue.
"The flue on the chimney was closed, causing smoke to move out into the room." "Damaging fires can occur when unburned material called creosote accumulates on the metal flue and in the upper chimney."
A FLUE is a chimney or vent. IE A flue was fitted to my central heating unit.
I am not writing a sentence using that word.
the flue pipe from my boiler runs directly to the hole in the chimney
I can give you a sentence using the word galaxy.
a sentence using the word endotracheal
This is a sentence using the word aviator.
I am saying a sentence using the word collagen.
This is a sentence using the word monomer. :P
this is a sentence using the word armchair.