How to comfort my sister who failed in the first round of interview in the Student Union?

Don't talk nonsense at this time, just take my sister to eat her favorite food, or take her to see a movie he likes very much. Just stay with her quietly, let her have a quiet time to transition her emotions and let him know that he is not alone. That's enough. If he really wants to tell us his grievances, then we will listen to him quietly, and then.