I am extremely sorry to tell you that I have no time to learn language by communicating with you. Therefore, I am writing to beg for your comprehension.
As the college entrance examination is approaching, my burden of study is becoming heavier and heavier, making it impossible to spend time talking with you, though you are my best friend from whom I trust. You have gained great progress in Chinese language skills, which makes it possible for you to make conversation with local Chinese. There is no doubt that you will wait until my graduation. Ever since then, I will spend more time with you heart to heart, which I think may contribute a lot to our relationship.
I am looking forward to your early reply.