I didn't learn well in the first day of junior high school, so the teacher asked me to repeat the grade because I was afraid of being laughed at by my classmates. What should I do?

I'm glad to answer your question. First of all, you can ask your parents and teachers to discuss whether you can not repeat the grade. Secondly, in the face of ridicule from others, the best way is to prove yourself with practical actions. There is another kind of people who think it's okay for others to laugh at your failing grades. Finally, we study hard, not necessarily worse than others, don't you think? Wish you success!