 Re: adverbial clause
It's not only about the article, but also the use of comma. I believe that we can treat it the same way as in sentences like:
I gave the book to a neighbor, who is tall
vs.
I gave the book to the neighbor who is tall
The second one, implies that we gave the book to the tall neighbor (and not the short one, for example).
Similarly, I think that
We went along a dirt road that led down into the valley where there was a pond implies that from all the valleys, the road led down into the valley where there was a pond.
At least that's how I would perceive the difference |