Dear Mr Cooper,
I work at the Friendhip Booktore on Dongfang Road where you often come to buy book.The other day when you bought a dictionary at our booktore I made a mitake abut the price.You looked at two different edition of the ame dictionary,one coting 30 yuan and the other 21 yuan.You took the 21-yuan but I accepted 30 yuan from you.I didn't find out my mitake until you had left.Will you pleae come to the booktore to get your change or to return your dictionary and get a 30-yuan edition intead? I apologize for whatever trouble thi i cauing you.
Your truly
Li Hua
亲爱的库伯先生，
我在东方路，你经常来买书的友谊书店工作。那一天，你在书店买了一本字典而我犯了一个价格的错误。你看了一本字典，两个不同的版本，一个是30元和另一本21元。你花21元，但我从手那晨接受了30元。直到你离开后我才意识到我的错误。请你到书店来找回你的零钱或拿回30元版那本呢？引起你的麻烦我感到很抱歉。
真诚的
李华