1. Thank you for your invitation: First of all, you can reply to the inviter by expressing your thanks, and you can simply say "Thank you for your invitation" or something similar.
2. Accept the invitation: If you are willing to attend the opening ceremony, you can reply to the other party to accept the invitation. You can tell the inviter that you are happy to attend and ask what preparations need to be made.
3. Decline the invitation: If you can't attend the opening ceremony, you can politely decline the invitation. You can tell the inviter that you are sorry to be unable to attend and express your wishes and congratulations.
4. Make suggestions: If you have any suggestions or questions about the opening ceremony, you can tell the inviter what you think. This can help the inviter to better prepare for the opening ceremony.
No matter which reply method you choose, you should express your thanks and blessings and wish the opening ceremony a complete success.