1. I am sorry that I couldn’t attend your party because…
2. I wish I didn’t give you too much trouble.
3. I regret that my carelessness has caused you too much inconvenience.
4. Much to my regret that…
5. I must apologize here…
6. I am writing to ask you for forgivingness.
7. Let me apologize here that…
温馨提示：
