Dear David，
亲爱的大卫，
I’m writing this letter to express my sincerely appologies to you for losing the book you lent to me. I’m very appreciated you lent it to me. In order to give it back to you as soon as possible, I took it to the library yesterday. I also borrow some other books in the library before I left. Unluckily, when I arrived at my dormitory, I couldn’t find your book. I searched all my dormitory and the road from the dormitory to the library. The next day I also looked for the library. However, I couldn’t find your book. I’m sorry I can’t give back to you on time as I promised before. But I will buy a new one for you later.Hope you can accept my appologies.
我写这封信是为了表达我对弄丢了你借给我的书的真诚的歉意。我很感激你把书借给我。为了能够尽快把书还给你，我昨天把它带到图书馆去看了。在我离开图书馆之前我也借了几本图书馆的书。很不幸的是，我回到宿舍后发现你的书不见了。我把宿舍，宿舍到图书馆的路都找遍了。 第二天我也去图书馆找了。可是，我就死找不到你的书。我很抱歉不能遵守之前的承诺按时把书还给你。但是我后面会帮你买一本新的。希望你能接受我的道歉。
Yours Sincerely,
Li Lei