Difference between Xはどこ and どこがX


I've been absorbing Japanese through osmosis for years, but I just started
learning it formally. The app I'm using presented these two sentences with the
same translation, I think just to show that the interrogatives like どこ can't
take は as their particle:

> 病院はどこですか Where is the hospital?  
>  どこが病院ですか Where is the hospital?

My question is, when would you use the latter? (My understanding is that the
first is more normal.) What's the difference in emphasis?

I think I get the difference for a different interrogator. If I understand
correctly, 先生はだれですか is neutral/putting emphasis on teacher, so it could mean
"Who (among us) is a teacher?" Whereas だれが先生ですか puts emphasis on "who," as in
"Just who _is_ that teacher." (I'm overemphasizing the distinction.) But I
don't see how that applies to どこ.




> A) 「病院{びょういん} **は** どこですか。」
>
> B) 「どこ **が** 病院ですか。」

The two sentences above surely have different meanings and usages.

As you stated, **A)** is the more "normal" or "versatile" sentence. It is used
to ask for the location of a/the hospital in a situation where the speaker has
little to no idea where a/the hospital might be in a town or area where the
speaker is a stranger. In fact, there might not even be a hospital there.

So, the replies to A) can be " _ **Turn left at the next traffic light and go
down a couple of blocks...**_." or " _ **I'm afraid there is no hospital
around here**_."

**B)** is used very differently in that both the speaker and listener know
that there is a hospital (nearby). Suppose you are looking at a campus map of
a medical school that you already know has a hospital attached to it. You want
to know exactly where on the campus it is located and the other person might
point a finger at the south-east corner of the map and reply 「ここ **が** 病院です。」
or just 「ここです。」.

A がｰanswer to a がｰquestion.

It could also be a small town or area to ask question B) in a situation where
you have a prior knowledge that there is a hospital there. Either you may have
had that knowledge for a long time or you have just learned it a moment ago.

Finally, A) can often replace B), but B) could not replace A) nearly as often.
That , of course, is because B) is more specific and A), more general. By
"specific", I mean to say that more specific situations/contexts are required
to naturally utter B) (as my example of a medical school map above).




> A) 「病院{びょういん} **は** どこですか。」
>
> B) 「どこ **が** 病院ですか。」

The two sentences above surely have different meanings and usages.

As you stated, **A)** is the more "normal" or "versatile" sentence. It is used
to ask for the location of a/the hospital in a situation where the speaker has
little to no idea where a/the hospital might be in a town or area where the
speaker is a stranger. In fact, there might not even be a hospital there.

So, the replies to A) can be " _ **Turn left at the next traffic light and go
down a couple of blocks...**_." or " _ **I'm afraid there is no hospital
around here**_."

**B)** is used very differently in that both the speaker and listener know
that there is a hospital (nearby). Suppose you are looking at a campus map of
a medical school that you already know has a hospital attached to it. You want
to know exactly where on the campus it is located and the other person might
point a finger at the south-east corner of the map and reply 「ここ **が** 病院です。」
or just 「ここです。」.

A がｰanswer to a がｰquestion.

It could also be a small town or area to ask question B) in a situation where
you have a prior knowledge that there is a hospital there. Either you may have
had that knowledge for a long time or you have just learned it a moment ago.

Finally, A) can often replace B), but B) could not replace A) nearly as often.
That , of course, is because B) is more specific and A), more general. By
"specific", I mean to say that more specific situations/contexts are required
to naturally utter B) (as my example of a medical school map above).

