One possible version:

Dear Miss Morgan,

I’m so sorry that I won’t be able to attend the lecture on American culture tomorrow afternoon.

My uncle is returning home from France , and I’ve promised to meet him at the airport at 3:30tomorrow afternoon.

I’m very interested in American society and culture. I wonder if it is possible for the talk to be recorded , and if so , could I borrow the tape?  It would mean a great deal to me to listen to the tape and make up for what is covered in the talk. I would appreciate it if you could allow me to ask for leave of absence.

Thank you .

Yours sincerely

Li Hua

题目分析：本篇书面表达是要求写一封信。同学们对于书信这种题材已经非常熟悉，而且要求内容比较简单。同学们在写作时要注意书信的格式要正确，不要遗漏要点，而且要适当补充细节以使行文连贯，顺畅。此外本文是向老师请假，要注意语言简洁明了，语气委婉客气。在时态方面要根据情况恰当选择。

【亮点说明】文章要点全面，结构紧凑。使用简单的语言表述了不能出席的理由以及自己的请求，叙述清晰明了，不拖泥带水。文中I wonder if it is possible for the talk to be recorded , and if so , could I borrow the tape?以及I would appreciate it if you could allow me to ask for leave of absence.等表述请求部分用词准确贴切，语气委婉礼貌，显示了作者对语言很强的运用能力。