Escribe. ¿Qué había hecho Andrés antes de matricularse en la universidad? Utiliza el pluscuamperfecto.

Antes de matricularse en la universidad, Andrés se había presentado a los exámenes finales.

Translation: Before enrolling in university, Andrés had taken the final exams.

Antes de matricularse en la universidad, Andrés había aprobado todas las asignaturas.

Translation: Before enrolling in the university, Andrés had passed all the subjects.

Antes de matricularse en la universidad, Andrés había hecho el examen de ingreso.

Translation: Before enrolling in university, Andrés had taken the entrance exam.

Antes de matricularse en la universidad, Andrés había buscado una residencia.

Translation: Before enrolling in university, Andrés had sought a residence.

Antes de matricularse en la universidad, Andrés se había marchado de vacaciones.

Translation: Before enrolling in university, Andrés had gone on vacation.

corras is the only one that is informal but doesn't follow the suffix rule. correr is the verb. corre is the formal verb form. corra would be used as the formal is corre ended with an a.

your best bet would be corras, it's the only one that is informal but is still wrong