Before revision:  Notably, the Spanish past subjunctive comes in two perfectly equivalent variants ended in -ra or -se (2 ); for instance, in the sentence 'If I were there', the verb can be equally translated to estuviera or estuviese. During a first spontaneous process that began in the Middle Ages, the form -ra migrated from the indicative to the subjunctive, displacing the original -se form (3-5) .
After revision:  Notably, the Spanish past subjunctive comes in two perfectly equivalent variants ended in -ra or -se (2 , 3). In the case of the Spanish past subjunctive, the evolution of its two competing forms (ended in -ra migrated from the indicative to the subjunctive, displacing the original -se form (3-5) .