"Are you at the train station?"
Translation:Bạn có đang ở ga tàu hỏa không?
Yes, that is the structure of Vietnamese question. Now I'm writing a discussion on Vietnamese question structure, maybe you'd like to see it. Here is the link.
Edit: Sorry, I've reread your comment and I think here is your concern: the sentence is closer to "You're at the train station, right?" than "Are you at the train station?". The meaning of those two sentences are the same, though there are a few differences (such as, you are more sure that he is at the train station). I can't find other structure that have closer meaning. And there are also some questions that does not need "phải", such as "Bạn thích cuốn sách đó không?". I'll do research on that and will update on my post on VNese questions.
I share this concern. I have not been taught that alternate word for train station yet, nor have I been taught đang, but for some reason I keep getting this question. Since it hasn't properly been taught to me I flunk it every time. This needs to either be taught prior or fixed.
bạn (có) ở nhà ga không? are you at the train station? you are asking a yes/no question
bạn ở nhà ga phải không? you're at the train station, right? you are seeking for a confirmation
if translated from "are you at the train station", Duo should have accepted "bạn (có) ở nhà ga không?"
[edit: Duo accepted không alone only if có was present. I just made the correction.]
This one puzzled me too, since (until now) it was always "nhà ga" as train station... but this seems to be a short version of "nhà ga tàu hỏa", which I found in a Wikipedia article about the Đà Lạt train station. It seems that "nhà ga" is meaning station or terminal and "tàu hỏa" is meaning train. With that in mind the solution above would make sense (but still it is an odd way to introduce new words, while ignoring the old ones).