dilate on/upon something
phrasal verb with dilate verb [ I or T ] uk/daɪˈleɪt/ us/ˈdaɪ.leɪt/
formal
详述；铺陈
to write or speak about a subject for a long time
He likes to dilate upon what he thinks is wrong with the world. 他喜欢滔滔不绝地谈他所理解的世界的问题所在。