You can send an email to the teacher saying that the respected teacher can't attend the summer camp for personal reasons. I hope the teacher will understand and give approval. The summer camp will send you an email to confirm your participation after the list is announced, and you can reply whether to participate or not according to your actual situation. If you miss this time and have an emergency, it is recommended to contact the relevant responsible teacher in time to explain the situation and leave the opportunity to those in need.