Really? I hope F stands for FANTASTIC

One of the many F's I have received on a Test. I really do wish F stood for fantastic not failure. But as always there are going to be some topics you don't understand, and sound waves was one of the concepts. I thought I understood the basics of the topic but once the test came up I went blank and didn't know what to do. All I hoped for was I would make some good guesses but apparently I didn't as you could see. I'm upset that I failed but I realized that I need to study more and not think I know the concept actually know for sure that I understand and I will pass when the next test comes up.