题目：
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 （1）. This, in turn, limits the data rate that can be carried on the transmission （2）. A square wave has an infinite number of frequency components and hence an infinite （3）. However, the peak amplitude of the kth frequency component, kf, is only l/k, so most of the （4） in this waveform is in the first few frequency components. In general, any digital waveform will have（5） 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.
（3）是（）
A.source
B.bandwidth
C.energy
D.cost
答案：
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参考答案：[参考例文] 贯彻科学发展观，促进各地区协调发展
