By the late nineteen fifties, folk music became popular again in the United States.

VOA: special.2010.06.20

Most of our popular music, folk songs and things like that, are written in duple meter and in a major key.

大多数的流行音乐,民歌,以及类似的音乐,是写在二拍子和大调上面

耶鲁公开课 - 聆听音乐课程节选

Artists of all ages joined Seeger on stage to sing the folk and protest songs that he made popular, like this one, "If I Had a Hammer."

VOA: special.2009.05.22