Dear Lihua,
I am writing to express my apology to you.I'm sorry to make you angry and sad,but i was not intended to do that.The pen i bought as a gift was very similar to the pen you sent to me as a present,so i sent it by mistake.I really cherish our friendship,and hope our friendship will last forever.Again,i apologize for my mistake.I 'm looking forward to your reply.
Yours sincerely,
Liming