Hi Sss, "to harp on" (phrasal verb) means to talk a lot about one particular thing, to the point that it becomes very annoying. It is an intransitive phrasal verb which means it is an action by itself. You could use it like this: "I hate it when my mum harps on about the laundry" "She was sitting there, harping on as usual" "Toby harped on about the rising taxes yesterday" I hope this helps! Take care, Triss

I think "harping on" is probably used more often than "harps on." Harps/harping on, is similar to nags/is nagging, complains/complaining, etc. Harps/harping on is when someone just won't "let go" of something. They bring up something you did in the past even though they say they forgave you or they just keep telling you to do something even though you said you would take care of it. She keeps harping on me about leaving the toilet seat up. She keeps harping on me to wipe the tooth paste out of the sink. My dad keeps harping on me to get a job (says a teenage son). I wish she would stop harping on me already!