【答案解析】Dear Tamia,
I am afraid that you will find me inexcusably rude for not answering your letter soon. Now I am writing to you these few lines to express my deep regret.
When I tell you the reason, I trust you will understand. When your letter arrived, I was in Qingdao. As my roommate could not forward it to me during my absence, it had been, therefore, lying on my desk until I returned.
I enjoyed various pleasant sights during my trip. I shall be pleased to give you an account of them when I see you next time.