1、effect 是名词，“影响”,搭配短语:have an effect on sth.=have an influence on sth.对··有影响affect 是动词，“影响”，直接跟宾语，affect sth 对···有影响，且通常指不利的影响。

2、eg, Sandstorms sometimes affect Bejing. Watching TV for a long time will have a bad effect on your eyes.