I am writing this letter to make an apology to you for I cant go out hiking with you tomorrow.The reason is that I will be occupied in an extremely important examination the day after tomorrow.To be honest,I am really looking forward to going out with you tomorrow.

　　It has been a long time since we came out together.Nevertheless, the exam is truly important.I must treat it seriously.I feel awfully sorry about it . What about another day.Waiting for your reply. Please allow me to say sorry again for my inconvenience I have caused.