just as是“正当...”的时候,也有“正像...”的意思 while 当...的时候(有时有转折意味) He was playing game while the others were doing their homeworks. 这里while表示同时性,也是前后两者的对比,翻译时可理解为“然而” when只是引导时间从句,没有感情色彩的.不转折.表示在...时. My uncle always come to visit me when he's not busy. 这句话里就不能用while或者just as,因为没有感情色彩.