What gets me as a non-native speaker far more than "a vs an" is the "a vs the" conundrum. I still don't quite get when something needs to be "indefinite" and I've been speaking English for close to forty years. My native tongue lacks articles altogether and it's soo bloody hard I feel hopeless I'll ever master them fully.
That rule isn’t universal though. “I go to the dentist every year” doesn’t imply that I particularly care about a specific dentist (or, case in point, about the specific dentist).
“This was a nice evening” is also difficult to characterize as not caring about which evening it is. As are books titled “An Introduction to XYZ”, where both the authors and the readers will probably care about the specific book.
Because you are referring to a specific one of each, even if a listener doesn’t necessarily know which specific one, they know that you know.
In the case of your example the listener assumes you mean whichever specific dentist you are currently seeing. That fact that you may choose one randomly each time is an exception.
abraxas · · focus · HN ↗
AndrewDucker · · focus · HN ↗
"Pass me a plate" - any plate will do. "Pass me the plate" - I want the specific plate which we were talking about.
layer8 · · focus · HN ↗
“This was a nice evening” is also difficult to characterize as not caring about which evening it is. As are books titled “An Introduction to XYZ”, where both the authors and the readers will probably care about the specific book.
nkrisc · · focus · HN ↗
Because you are referring to a specific one of each, even if a listener doesn’t necessarily know which specific one, they know that you know.
In the case of your example the listener assumes you mean whichever specific dentist you are currently seeing. That fact that you may choose one randomly each time is an exception.