I want to learn how to pronounce it too!
This page might be of help:
I put "a happy girl sweats." How is that different? Is there a way to define "a" vs "the"
Personally, on paper, your answer should have been correct. Though, just like many of the sentences on Duolingo, you would never need to say that in your life time. And as for "A" and "The" I believe they are interchangeable.
I dont know
It is only different by context.
And the pronunciation guide is on the Duolingo web app.
I can't ynder stand it no matter what!!!