I had big mustake

I had big mistake. I had big score in most of spring class,but I hadn't good way of study. I had wanted only the score in spring class. Good way of studying is really understanding. I had big mistake. I had thought that studying is not hard and, hearing class is good way. I had thought that studying is hearing only. I am ashamed. This is really stupid. I must undersatnd about studying. That's is problem of mine. I do my best. Thank you. Tomofumi kamegawa