Help:international conference

How to call a person you meet at an international conference?
1)If you know his name, and you know he is a prof.and Dr.
   Prof. ***?
2)If you know his name, and you know he is a Dr., but you do not know if he is a prof. or not
   Dr. ***?
3) If you know his name, but you do not know if he is a Dr.or not
   Mr. ***?  
Thx!

yeah, it might be possible to find the title of someone from the documents
but when u get to know a new person,u can only have his name after his introduction

在實驗室里的情況和你說的情況是不同的,在實驗室還可以直呼老闆的名字呢.

我比較同意Adelyn的說法, 不太熟悉的情況下, 揀你所知道的較高的職稱稱呼.

在美國,如果一個老闆既有MD又有PHD, 他比較喜歡你叫他DR.的. 如果沒有MD的老闆,會比較喜歡你叫他Prof.
(在實驗室,試想如果你在老闆手下做事,你叫他的稱呼比他應該的稱呼高,老闆固然會高興一下, 但傳出去就是笑話,沒有老闆會讓你一直亂叫下去的. )

International conference你應該可以在會議資料里找到他的稱呼.

Thank you! Adelyn
  I also asked one of my friends in US, but he said in his lab they never call a prof. Prof. but Dr.because Dr.shows more respect than Prof.
  Is it?

Hi chkou,

You should call him Prof. Jones if he is a faculty member of a university or a college. In all other situations, you may call him Dr. Jones (even if he doesn't have a phd I am pretty sure he will feel flattered and like it). You should never call him Mr. Jones if you don't want to lose any opportunities.