Now Sungil has asked about the difference in meaning regarding the tenses of the "If I were elected" and the "If I be elected" examples stated in my answer above. First, Sungil, the subjunctive is not a tense; it's a mood; therefore, these verbs are not inflected into a tense, but inflected into a "mood"—the subjunctive mood to be exact. The "If I be elected" example is the present subjunctive and it's very formal bordering on archaic, just to let you know. It differs from the "If I were elected" example insofar as the "I be elected" one expresses a real possibility in the present whereas the "I were elected" one expresses something that is contrary to fact in the present. Apparently, it is possible that I may be elected President, so "if I be elected" President, I shall cut taxes. Since the chances are slim that I shall ever be elected President, I would most likely say, "'If I were elected' President, I should cut taxes," since it is nearly impossible for me ever to be elected President. If I were a politician like Hillary Clinton or Ted Cruz or Mike Pence, it would probably be possible then and the very formal/archaic "If I be elected" example would prevail. In Modern English, the present subjunctive seldom occurs after a subordinating conjunction anymore except in very formal speech and prose normally. It can occur in much more informal settings, but not too often.
In any event, that's the subtle difference between them, Sungil. The present subjunctive in "if" clauses talks about real possibilities in the present and the past subjunctive talks about counterfactual situations in the present.