Lemme vent for a bit gengeng cuz im lowk fr wnna cry twin

Why is it that when I work hard and focus on studying for 4-6 hours but then when the professor calls on me for the oral exam, the one thing he asks is the simplest topic that I didn’t study? And then a classmat who I know barely studied gets it correct. I’m just so frustrated not just about that exact moment but about the overall pattern of what I’ve been experiencing. Believe it or not it’s always like this. I really want to cry. I work hard. I’m not the smartest in the class, but I still worked hard for that. I did everything right, so why does it feel like it doesn’t pay off? I honestly want to cry.