For this part, you are supposed to write a letter in English in 100-120 words based on the following situation. Remember to write it clearly. 你的朋友(Tom)请你(Li Yuan)周末和他一起去承德的家里玩儿，但你有事不能去。请你用英文给他写一封信，内容包括： (1)感谢他的邀请。 (2)说明不能去的原因。 (3)为不能去表示遗憾。
【正确答案】Dear Tom, Thank you so much for inviting me to go with you and see your family at Chengde this weekend. I've heard a lot about your kind and warm-hearted parents from you and hope to see them for a long time. And chengde is a beautiful city I dream to visit. But I have to say sorry that I cannot go. Unfortunately, my uncle is coming to see me this weekend on Saturday and on Sunday I have an English exam. So, I have to stay here. I do hope that we can do it another time. Please send my best wishes to your parents. Thank you again and take care. Yours, Li Yuan