Can a 9-year-old boy wear a Chinese-style chest covering naked when performing?

No, he is very old at the age of nine. He knows something. If he doesn't wear it, it's not good for his growth. He can talk to the teacher to understand the truth, that is, parents see that taking pictures and the like are not good for the teacher's future and reputation, and he can only pay attention to the teacher's own interests. Besides, the class performance is not a national performance. If it is to be restored, the national performance will not be so standard. It is more important to pay attention to children's mental health. This teacher wants to make trouble. Otherwise, the Chinese-style chest covering will be longer. In short, don't show the key parts.