Impersonal, single vs. plural
 

Hi,

Are they unconditionally interchangeable?

—Esta mañana no se pronosticaba lluvia —
dijo Ben, intranquilo—. El diario anunciaba
caluroso y seminublado.


Is it correct to change it to se pronosticaban? Why am I asking? I've never seen que dan in singular, but I have not read enough to be sure :)

The impersonal 'se' construction always takes a third-person singular form.

Thanks! Without se as I wish?

Yes.

—Y después se cuentan chistes.

Is this impersonal?

No, this is a reciprocating (mutually inclusive/circular) form. The conversationalists are telling each other jokes.

This is one of the hardest things I've ever had to explain, because I have a hard time trying to distinguish one from the other myself, so don't despair if it's not clear for a while. ;)

This is a case of "voz pasiva refleja", which is close to an impersonal, but there is number agreement with the transitive verb. So you can say "se pronosticaban lluvias", because the agreement is made with the "patient subject" that receives the action.

- Se pronosticaba lluvia. :good:
- Se pronosticaban lluvias. :good:
- Se pronosticaba lluvias. :bad:
- Se pronosticaba tiempo nublado. :good:
- Se pronosticaban nublados parciales. :good:

Impersonal:

- Se ve que ha llovido. -> There is no subject, and no actual patient subject that is seen.
- Se vive bien en esta ciudad. -> There is no explicit subject that lives well, and the verb is intransitive.
- Es bueno saber que no se envejece del corazón. -> (It's good to know the heart doesn't grow old.) -> Although it's understood it's the heart that doesn't grow old, there is no actual subject in the sentence.
- Aquí no se respeta a nadie. -> When the patient subject is a person introduced by "a" then the construction becomes an impersonal, instead of "voz pasiva refleja".


Voz pasiva refleja:
- Se ve la lluvia desde la ventana. -> The passive subject is the rain that can be seen from the window.
- Se viven muchas historias en esta ciudad. -> The patient subject are the stories lived in this city.
- Cuando se envejece, se aprenden más cosas. -> First part of the sentence is an impersonal, but in the second part of the sentence the patient subject are the things learnt.
- Aquí se respetan todas las ideas. -> All ideas are the patient subject of a transitive verb that is not a person.
- Y luego se cuentan chistes. ;) (Although, as Rusty said, this may be a reciprocal, when you already know that two or more people are interacting to tell jokes to one another).

Thank you very much, Angelica! Very interesting and far less cryptic than the redundant object pronoun :)

What's your English translation for se ve que ha llovido? I have a pretty good idea about the actual meaning; just don't want to be overconfident :)

I'm not sure about a translation, but the idea is that "it is obvious that it has rained", "it's plain to see that it's been raining".
Last week the grass in the park was mostly dry and dirt was loose. After a week of heavy rains, "se ve que ha llovido", because the grass is green and tall and the dirt is rather mud. ;)

It's a bit awkward in English, yes. On the other hand, in Russian it's straightforward: "видно, что прошел дождь" :)