【答案解析】Dear Bob, I am so sorry to say that I forgot to return your music CD. I am writing this letter to express my regret to you. Several days ago, I borrowed your music CD when I lived in your house. Unfortunately, after I came back from Canada, I found it in my luggage. I am going to send it back to you as quickly as possible. And then I'll give you a call. If necessary, I will compensate for any trouble caused. once again, I feel so sorry for any inconvenience caused. Please accept my apologies. 　 　　　　　　　　　　　　　　　　Truly, 　　　　　　　　 　　　 　　　　 Li Ming