What is the difference between と言えば, って, が, and なら for discussing something previously mentioned?


Quartet says that in this usage of なら, you're establishing a topic by directly
quoting a noun mentioned by someone else. Why would this even be necessary? If
someone says to me "駅はどこですか," haven't they already extablished 駅 as the topic?

According to Quartet, "駅なら、病院のとなりですよ" is a correct and natural response. How
is using NARA here better than って or just が?

The section in Quartert immediately preceeding なら is と言えば. This also seems to
perform exactly the same funtion as って and なら. Does it not?

Would someone be able to clarify these words and their usages?




なら is not necessary. は is perfectly fine.

> 駅は病院のとなりですよ。  
>  The station is next to the hospital.

You can also omit the topic altogether, of course.

> 病院のとなりですよ。  
>  It is next to the hospital.

Using なら, you would sound like you are explicitly stating the assumption on
which you are going to provide an answer, which is not really necessary but
doesn’t particularly sound redundant, either. Remember that なら is basically a
conditional expression.

> 駅なら病院のとなりですよ。  
>  If you want to know about the station, it is next to the hospital.

が is inappropriate here. Your response would sound like an answer to what is
next to the hospital, rather than where the station is located.

> 駅が病院のとなりですよ。  
>  It is the station that is next to the hospital.

って is a short and somewhat colloquial equivalent of というのは. You would use it to
cite some concept you are not familiar with or quote something someone has
just said when you want to ask about or comment on it. It would be acceptable
to ask 駅ってどこですか in informal settings, but if you use it in the response, you
would sound like you are, depending on the tone, either puzzled or disgusted
at what you see as a silly question.

> 駅って、病院のとなりですよ。  
>  Station? (What?) It is next to the hospital.

と言えば is used to introduce a new topic that is related to what is mentioned. It
would sound terribly out of place if what follows is a direct response to what
the other person has just asked.

> 駅と言えば、病院のとなりですよ。(?)  
>  Speaking of the station, it is next to the hospital. (?)

