The prototype of this article is actually a classmate of mine. One day the teacher asked him to answer a question and he stood up and said weakly to the teacher. . Teacher, I can't see the courseware. . I have dense syndrome. . I was instantly struck by this strange symptom. . Later, Du Niang found out that it was not a serious disease - - but she still felt so cute that she couldn't help but feel itchy and wrote this article =W=