开头部分：【书信第一段包含四种内容：问候、自我介绍、写信背景、写信目的】

How nice to hear from you

Let me tell you something about the

I’m glad to have received your letter of

I’m pleased to hear that you’re coming to China for a

I’m writing to thank you for your help during my stay in

结尾部分：【最后一段一般包含：期待回信、感谢、祝福等内容】

With best

I’m looking forward to your

I’d appreciate it if you could reply