设计问候与介绍的情景对话，高手来吧，你一定会有福报的哟。

Any dialogue needs small talks and communication topics. As for greetings and introductions, you can make a dialogue based on the personal information, such as his family, job, hobbies, hometown,etc, anything that can spread the talk without touching taboos topics.Give you an example.
当中介人介绍时：Mr. Smith, I would like you to see a friend of mine. This is Zhangyu. He is the HR assistant from our department.(职位) We have known each other for 5 years.(诸如此类)
跟久未谋面的老朋友打招呼：Hey, Jane, long time no see! It has been 3 years since last time we met. How have you been?/ How is everything?/How are you doing?/ Where have you been for these years?(it can be any questions you want to know.)
送别：It could be years since this departure. Let's keep intouch./Please do take care of youreself . /Don't forget to wrtie/call to me. I will miss you. /
Have a nice/safe trip!(任何表达情意与祝愿的句子)

这些只是我经常会用的。你可以上网搜搜，疯狂英语啊什么的都有好多这样分类的口语情景对话及常用句型，蛮管用的。

不知道，虽然编对话我很擅长，但是这个对话我就不行了，有点难度的。