【单选题】According to the passage, which of the following statements is NOT true?
A.
It is not quite easy to tell how " rock and roll" began.
B.
Both the blues and country music were developed by the musicians in the southern United States.
C.
Both the Europeans and the African slaves came to America during the 17th century.
D.
It was the blues songs recorded in Memphis that made Elvis Presley popular throughout the nation.
【单选题】According to the text, which of the following statement is NOT TRUE?
A.
It is not easy to tell how “rock and roll” began.
B.
Both the blues and country music were developed by the musicians in the southern United States.
C.
Both the Europeans and the African slaves came to America during the 17th century.
D.
It was the blues songs recorded in Memphis that made Elvis Presley popular throughout the world.
【单选题】对生产经营单位安全生产管理人员的能力要求,《安全生产法》规定,生产经营单位的主要负责人和安全生产管理人员必须具备与本单位所从事的生产经营活动相适应的( )。
【单选题】并励电动机,PN = 37kW,UN = 440V,IaN = 97A,Ra = 0.332Ω,pf = 1496 W,则p0应为[ ]。
【简答题】在设计一个有抗震设防要求的框架结构中,有的设计人员在绘制施工图时,任意增加计算和构造所需的钢筋面积,认为:“这样更安全”。但是下列条件中,哪一条会由 于增加了钢筋面积反而可能使结构的抗震能力降低?( )