美国留学申请，网申推荐人那一块，relationship一栏怎么填

"Supervisor"
You have to fill in "who this person is to you". What is his/her relationship to you. 他是你的甚么人。不是与你有何关系 （relationship "with" you).
Other examples: sister, father, grandfather, cousin, friend, teacher, neighbour, aunt, mother, mentor....

Do not write "very close" or "not so close"， etc. Some people interpret the meaning of relationship as "关系”, then fill in "很密切”、"不怎么样"、“还可以”、“在发展中”。

added its tuneful drop to noisy deluge that 

比如 professor；employer 就是指你的雇主啊，你是有工作经验，你要写你的雇主是你们单位领导

更多留学信息和难题的解决方法我私信你，你看下，祝您幸运~