求翻译：然后我来说下它的发展历史，19世纪期间音乐是美国南部种植园黑人奴隶们表达自我生活和情感的重要手段。从19世纪末开始，爵士乐以英美传统音乐为基础，混合了布鲁斯、拉格泰姆及其它音乐类型，是一种“混血”的产物。美洲的黑人音乐保存了大量非洲特色，节奏特色明显，而且保留了集体即兴创作的特点。是什么意思？

Then me under its development history, the music of the 19th century Southern plantation blacks slaves is an important means of self-expression, life and emotion. Beginning in the late 19th century, jazz-based Anglo-American traditional music, a mix of blues, ragtime and other types of music, is the

And then I have to say that the history of the development, and its 19th-century music is south of the United States during slavery, plantation life and the emotional self-expression. From the beginning of the 19th Century, British and American jazz to traditional music, mixed with the blues, and ot

Then my under its development history, the 19th century period music is south US the plantation black slaves expresses the self-life and the emotion important method.Starts from 19 century's ends, jazz take the British and American tradition music as a foundation, mixed Bruce, Ragtime and other musi

And then, for me it's development history, during the 19th century music are United States black slaves on southern plantations are important means of expression and emotional self-life. Starting from the late 19th century, jazz based on the traditional British and American music, mixing blues, ragt

正在翻译，请