prate       
verb [ I ]  old-fashioned uk/preɪt/ us/preɪt/ (also prate on)
 侃侃而谈,对…滔滔不绝
to talk stupidly, or about things that are not important, for a long time
  Inevitably there's some caller prating on about the decline in moral standards. 不可避免会有人打进电话来侃侃而谈道德沦丧问题。 
 Synonyms: chatter prattle 
Compare: gabble verb gibber blabber blab