题目内容：
根据下列文章,请回答题。 Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C or D on ANSWER SHEET 1.Music comes in many forms; most countries have a style of their own. _______21 the turn of the century when jazz (爵士乐) was born, America bad no prominent ______ 22 of its own. No one knows exactly when jazz was ______ 23 , or by whom. But it began to be______ 24 in the early 1900s.Jazz is America' s contribution to ______ 25 music. In contrast to classical music, which ______ 26 formal European traditions. Jazz is spontaneous and free-form. It bubbles with energy, ______ 27 moods, interests, and emotions of the people. In the 1920s, jazz ______28 like America. And 29 it does today.
The ______ 30 of this music are as interesting as the music ______ 31 , American Negroes, or blacks, as they are called today were the Jazz ______ 32 . They were brought to the Southern states ______ 33 slaves. They were sold to plantation owners and forced to work long ______ 34 . When a Negro died, his friends and relatives ______ 35 a procession to carry the body to the cemetery. In New Orleans, a band often accompanied the ______36 . On the way to the cemetery the band played slow, solemn music suited to the occasion, ______ 37 on the way home the mood changed. Spirits lifted. Death had removed one of their ______38 , but the living were glad to be alive. The band played ______39 music improvising (即兴表演）on both the harmony and the melody of the tunes ______40 at the funeral. This music made everyone want to dance. It was an early form of Jazz. A．Before
B．At
C．In
D．On
参考答案：
答案解析：