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问题 选择题

从二战结束后到20世纪70年代初期，美国经济发展进入“黄金时期”。美国经济这一时期迅速发展的主要原因是（   ）                                          
A．奉行凯恩斯主义

B．注意减少国家对经济的干预
C．推行社会福利政策，建立“福利国家”，缓和了阶级矛盾
D．“新经济”的胜利

答案

A

略

单项选择题

会计档案保管期限分为永久和定期两类。下列属于企业永久性保管的会计档案是( )。

A．原始凭证

B．会计档案保管清册

C．总账

D．会计移交清册
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单项选择题

Although a given waveform may contain frequencies over a very broad range, as a practical matter any transmission system will be able to accommodate only a limited band of (86) . This, in turn, limits the data rate that can be carried on the transmission (87) A square wave has an infinite number of frequency components and hence an infinite (88) However, the peak amplitude of the kth frequency component, kf, is only l/k, so most of the (89) in this waveform is in the first few frequency components. In general, any digital waveform will have (90) bandwidth. If we attempt to transmit this waveform as a signal over any medium, the transmission system will limit the bandwidth that can be transmitted.

（90）是（）

A.small

B.limited

C.infinite

D.finite
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