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问题 填空题

一个由8个10、7个1、6个0.01、5个0.001组成，这个数写作______．

答案

由8个10、7个1、6个0.01、5个0.001组成的数是：87.065．

故答案为：87.065．

填空题

依据所学的化学知识解答：

(1)将墨汁滴入一杯清水中，清水很快变黑，说明________________________；

(2)铁在空气中容易生锈，这是因为________________________________(用化学方程式表示)，防止铁制品锈蚀的方法有________(写一种即可)；

(3)若装白磷的储罐起火，可以用水灭火，也可以用沙土填埋灭火。其中用沙土填埋灭火的原理是________________________________。
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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 （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.

（2）是（）

A.procedures

B.function

C.route

D.medium
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