Spanish question

I’ve been teaching myself Spanish for about a year now, but I think I’ve been confusing the conditional tense and the imperfect subjunctive tense. Could someone tell me the difference between, for example:

poder: podria vs pudiera

saber: sabria vs supiera

decir: diria vs dijera

There is an Enrique Iglesias song where he sings “Yo pudiera ser tu heroe,” and that’s why I’ve been using “pudiera” to mean “could.” When does one use podria?

I would know the answer if you would tell me.
Yo supiera (or yo sabria?) la repuesta si la me dijeras (or dirias?).

So what’s the difference?

Si me dijeras la respuesta la sabría. If you told me the answer then I would know it
Si supiera la respuesta te la diría. If I knew the answer then I would tell you
Hmm. . . Supiera is more like the independent conditional variable while sabría is the dependent variable.

I have no idea what I’m talking about. I just speak the language. maybe I am mixing grammar with algebra.

Pretty much what Sailor said - I’ve never heard a simple definition of subjunctives but basically they’re used in subordinate clauses :

I would tell you (conditional) if I knew (subjunctive).

You still see them in english too from time to time, (eg) but you would hate me if I were to tell you when.

I wouldn’t do that if I were you

If you check a grammar book it’ll tell you the thousand and one places to use them - most common are in clauses after creo que, * parece que* , se puede que, the if/then type structure from your example, conjecture, possibility etc

Conditional is the direct equivalent of English would, should, could

Now we’ve got that worked out, maybe somebody can tell me when to use ser and estar

When to use ser and estar:

http://www.orbilat.com/Modern_Romance/Ibero-Romance/Spanish/Grammar/Spanish-Verb-Auxiliaries.html

Related to this, when I was reading Hamlet in Spanish, the original translation had the beginning of the famous line as : “Existir o no Existir, he ahí la cuestión!” (To exist or not to exist! That is the question!)

Later translations showed the line as “Ser o no Ser”, which was the most popular way the line was translated in Spanish movies and TV. Showing that even academia gives in to mainstream media.

Searching for the lyric I find that the full line is “si yo pudiera ser…” --if I could be–which is the, uh, conditional imperfect subjunctive tense. You’d use “podría” if you removed the conditional “if”… as in, I could go to the store.

But to complicate things, at least in usage sometimes the perfect tenses are interchangeable. “I would have gone” logically should be the conditional perfect “yo habría ido”, but is often expressed as the third conditional “yo hubiera ido” or even the past imperfect “yo iba”. Same occurs for tenses like “you should have gone”–grammatically correct to say “debiste de haber ido” or even “debiste ir”, becomes “hubieras ido”.