作文还是要自己写的呢，可以更好的掌握学到的单词和短语

这个给你参考一下：

Dear Tom,
       Thank you for your last letter.In your letter you asked me to introduce myself. Let me tell you what is my favorite sport. I like playing sports, such as soccer, badminton and so on. But in most sports, I like basketball best. Because the basketball can make me happy, and playing basketball is good for our health. In the future, I want to be a professional basketball player, like Yaoming. So I practice basketball every day.
       What about you? What's your favorite sport? Pleas write to me soon.
                                                                                                  Yours,
                                                                                                   Li hua