pick someone up on something
phrasal verb with pick verb uk/pɪk/ us/pɪk/
在…上挑(某人)毛病,指出(某人)在…方面的错误
to criticize someone about something they have said
"I want to pick you up on the point you made a few minutes ago about personal morality, Archbishop." “大主教,我对您刚才有关个人道德的观点有不同的意见。”
His teacher picked him up on his pronunciation. 他的老师指出了他的发音错误。