His mother taugh __ ,but his father was a only a blue-collar worker.为什么要填piano,不填the piano

His mother taugh __ ,but his father was a only a blue-collar worker.为什么要填piano,不填the piano
His mother taugh __ ,but his father was a only a blue-collar worker.为什么要填piano,不填the piano

His mother taugh __ ,but his father was a only a blue-collar worker.为什么要填piano,不填the piano
His mother taught （piano）,but his father was a only a blue-collar worker.
他的母亲教钢琴课,但他的父亲只是一名蓝领工人.
the piano,加了定冠词的piano指的是一种乐器.没有定冠词的则是指一门课程.可以教一门课程,但不能教“乐器”学知识.乐器不能作为teach的宾语.

教书 teach school
加the 也不是不行，就是指在特定的一所学校教书
你这句teach piano是教钢琴，加上the那就是说只教那个钢琴？呵呵，完全说不通的