[填空题]When Negro Jazz bands became popular, the white musicians became interested and began to imitate their style.

[填空题]Since the time of ODJB, jazz became more popular, some jazz band even had musicians with______.

[填空题]When Jazz came into being at first, it soon became popular and was accepted by the upper-class.

[单项选择]
Central heating became popular only after the Civil War. Typically, coal-burning furnaces (火炉) fueled the early systems. Natural gas had developed into the leading fuel by 1960. Its acceptance resulted in part from its wide uses. Because it comes primarily from U.S. and Canadian fields, natural gas is also less vulnerable(脆弱的)than oil is to War. Oil remains the most important fuel in a few areas, such as New England.
Electric heating dominates most areas with mild winters and cheap electricity, including the South and the Northwest. It was made popular at least in the South by the low cost of adding electric heating to new houses built with air-conditioning. Bottled gas, which is somewhat more expensive than utility gas, is the fuel of choice in rural areas not served by utility pipelines. Wood is the leading heating fuel in just a few rural counties.
Home heating, which accounts for less than 7 percent of all energ
A. 1978
B. 1960
C. 1997
D. 2000

[填空题]Cigarettes became popular in Europe by the late 1500s.

[单项选择]As automation became popular in most factories, labor was made（　）.
A. destined
B. redundant
C. diverse
D. discontent