单选题 "Is jazz a kind of folk music? Is it a performing style? How is it different from other kinds of music?" There is no simple answer to these questions, because the most important quality of jazz comes from its unique combination of different musical sources over a period of almost 400 years.
The quality that unites the many different jazz forms is, in some degree, separate from its musical sources. That quality is the expression of freedom. The idea of freedom is central.
The ancestors of jazz were black people from West Africa who were brought to America as slaves, or forced laborers, from the early 1600s to the mid-1800s. Most of them remained slaves until President Lincoln set them free on January 1, 1863, at the midpoint of the American Civil War.
With the less of their personal freedom and the breaking up of their families, the slaves also borrowed the social traditions of their music from Africa. The complex rhythms of this music involved a number of people performing together. The breaking apart of these social groups forced slaves to create new songs--that is, to develop a completely new musical tradition.
Using some of the remembered African rhythms, the slaves gradually began to add some features of the European classical music that was played by the white slave owners. The slaves were also influenced by American folk songs. But the result of adding these borrowed elements to the complex African rhythms was the beginning of a completely new kind of music. Still, this music only existed privately among groups of slaves.
The slaves' work had another effect on their music. It introduced new kinds of music rhythms. Some of these rhythms became work songs to accompany their planting end picking of cotton. Other rhythms were developed by teams of workers who needed to lift heavy loads of cotton onto carts that passed through the fields. Later, during the building of the railroads, individual workers created new songs to match the sharp rhythms of steel striking, as they fixed the rails into place.

单选题 The main musical sources used by file slaves to develop a new kind of music were ______.

单选题 In some degree, the quality that the many different jazz form sham is ______.

单选题 "It introduced new kinds of musical rhythms" (in the last paragraph). Here "it" refers to ______.

单选题 When the slaves lost their personal freedom and their families, ______.

单选题 Which of the following statements is NOT true?