求一片 英文的 资料或者演讲稿 关于摇滚的 例如起源、发展、分类、影响等等

Rock-and-Roll (rock n'roll) n. first so used (1951) by Alan Freed, Cleveland disc jockey, taken from the song "My Baby Rocks Me with a Steady Roll". The use of rock, roll, rock and roll, etc., with reference to sexual intercourse, is traditional in blues, a form of popular music that evolved in the 1950's from rhythm and blues, characterized by the use of electric guitars, a strong rhythm with an accent on the offbeat, and youth-oriented lyrics.