【正确答案】 Dear Ms. Wang,
I am writing to apologize for the fact that I failed to hand in the homework of your writing class on time yesterday.
The day before yesterday, the photography association held a field trip to Suzhou to take pictures for the coming photography competition. As the president of the association, I had to be in charge of the whole activity as well as take care of our members. It was 1 o'clock a.m. when I got home. Having a very tight schedule the whole day, I felt so tired that I fell asleep once I arrived home, failing to finish the homework.
I know I should balance work and study well. I would never let this happen again and I will hand in my homework as soon as possible.
Yours Sincerely,
Li Ming

【答案解析】本文要求给老师写一封道歉信，解释未能按时交作业的原因。文章内容安排如下：
第一段说明问题，表示歉意。
第二段作出解释，说明未能按时交作业的原因。
第三段说明自己对错误的认识并做出承诺。