Use of the Imperfect Subjunctive
Hi,
I was just wondering if someone could explain why in the sentence below
Facebookeros argentinos reflejan la decepción por Obama un año después de que se convirtiera en presidente.
the Imperfect Subjunctive is used and not just the Preterit. I can understand why you would use the subjunctive after "después de" in the present tense as there is an element of doubt that it may or may not happen, but in this case Obama DID become president so why the need to use the imperfect subjunctive?
Thanks in advance for any help! Dan
4 Answers
lazarus has made a few posts on related subjects:
A) La gente se impacienta porque tiene muchos problemas.
B) El hecho de que alguien tenga problemas no justifica que se impaciente
Clearly, the person B is not trying to inform A about the people becoming impatient or having problems (since it is A who mentioned it) , but about our views on whether such facts are justified. That piece of information about our thoughts that we want to share is a declaration; previously known or assumed to be known facts are not.
But we don't need previously known facts for non-declarations. It is enough that we don't want to make the statement in a clause the main point of our conversation, simply because we are going to make a comment about it; a comment that it is the one that will mark the main point of the conversation
There was another post where he explained that the use of the subjunctive was grammatically incorrect in some cases, but widely used anyway because it sounded right. It was about an article where the subjunctive was used to describe a past event that had happened, but I can't find the link.
And look here
Can someone provide examples of common uses of the imperfect subjunctive?
One very common example in with the contrary-to-fact "if" clauses.
In contrast, an unreal or contrary-to-fact condition is one which will not come about or is viewed as being completely hypothetical. In this case, the “if” clause in normally in a past subjunctive tense, and the main verb is in a conditional tense.
Present or future time situations. The imperfect subjunctive is used in the “if” clause, and the conditional in the main clause:
Si yo fuera rico compraría un coche.
If I were rich [I am not rich] I would buy a car.
¿Qué harías si fueras presidente?
What would you do if you were president? [you aren't]
Si Juana estuviera aquí, ¿le dirías la verdad?
If Juana were here [she isn't here], would you tell her the truth?
We have some previous threads that explain the historical development or the se and ra forms of the imperfect subjunctive, but the salient points are:
the ra form is most commonly used
the two forms are interchangable except that there exists constructions where one is preferred over the other just from common usage.
Would it be because he hasn't finished being the president yet? The action isn't completed? Just a guess 
In general, if the situation in the adverbial clause is viewed as something hypothetical or anticipated —rather than completed, habitual, or factual— then the subjunctive is required.
In contrast, if the adverbial expression deals with something that is viewed as completed, habitual, or factual, the indicative is used. Some adverbial conjunctions by their very nature deal with something hypothetical or anticipated and thus are always followed by the subjunctive; others may take either the subjunctive or the indicative.
The question is about the imperfect subjunctive not the present subjunctive. I for one would like to see this question answered as I'm uncertain about the imperfect subjunctive as well. Can someone provide examples of common uses of the imperfect subjunctive? The text book I'm reading says its optional and gives nothing but the endings and doesn't even explain why there are 2 forms (-se and -re) for all three types of verbs (i.e. -ar,-er,-ir) Any help here will be appreciated.
