审：人称：第一人称.时态：一般过去时.体裁：道歉信

列：failed to attend your birthday party.the day before yesterday.the final exam.was occupied preparing for the exam.forget the appointment.have a get- together.make up for my careless mistake.accept my sincere apologies

润：定语从句：as I had promised时间状语： On receiving your invitation, I felt extremely happy and excited.so...that...:I was so occupied preparing for the exam that I forgot the appointment.

so that:Could we find a suitable time to have a get- together so that I can make up for my careless mistake.主语从句：It is much to my regret that I missed the chance.

范文：Happy birthday to you. I’m sorry that I failed to attend your birthday party the day before yesterday as I had promised.On receiving your invitation, I felt extremely happy and excited. Unfortunately, with the final exam around the corner, I was so occupied preparing for the exam that I forgot the appointment. I can imagine how disappointed you were when I didn’t turn up. Anyway, the exam over, could we find a suitable time to have a get- together so that I can make up for my careless mistake?It is much to my regret that I missed the chance. Once again, please accept my sincere apologies!