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问题 单项选择题

采用相一幅调制(PAM)技术在带宽为32kHz的无噪声信道上传输数字信号，每个相位处都有两种不同幅度的电子。若要达到192Kb/s的数据速率，至少要有 (11) 种不同的相位。

A．2

B．4

C．8

D．16

答案

参考答案：B

解析：[要点解析] 对于无噪声的信道可利用奈奎斯特公式C=2Wlog2N来计算信道容量，其中W指信道带宽。题目中已给出W=32kHz，C=192Kb/s，因此：[*]
那么N=23=8。又由于所传输的数字信号每个相位处都有两种不同幅度的电平，因此所求相位种类 N1=N/2=4。

单项选择题

Anthropology is the study of human beings as creatures of society. It (1) its attention upon those. physical characteristics and industrial techniques, those conventions and values, which (2) one community from all others that belong to a different tradition.

The distinguishing mark of anthropology among the social sciences is that it includes for serious study other societies (3) our own. For its purposes any social (4) of mating and reproduction is as significant as our own. To the anthropologist our customs and those of a New Guinea tribe are two possible social schemes for (5) a common problem, and in so far as he remains an anthropologist he is (6) to avoid any weighting of one (7) the other. He is interested in human behavior, not as it is shaped by one tradition, our own, but as it has been shaped by any tradition (8) He is interested in a wide (9) of custom that is found in various cultures, and his object is to understand the way in which these cultures change and (10) , the different forms through which they express themselves and the (11) in which the customs of any peoples function in the lives of the (12) .

Now custom has not been commonly regarded as a (13) of any great moment. The inner workings of our own brains we feel to be uniquely (14) of investigation, but custom, we have a way of thinking, is behavior at its most commonplace. (15) , it is the other way round. Traditional custom is a mass of detailed behavior more astonishing than (16) any one person can ever evolve in individual actions. Yet that is a rather (17) aspect of the matter. The fact (18) first rate importance is the predominant role that custom (19) in experience and belief, and the very great varieties it may (20)

7（）

A. in favor of

B. instead of

C. rather than

D. in contrast with
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选择题

初次分配和再分配都要兼顾效率和公平，再分配更加注重公平，从而实现发展成果由人民共享。下列举措中能体现再分配更加注重公平的是

①某市企业最低工资标准由每月1260元调整为1400元

②某公司建立根据经营管理绩效、风险和责任确定薪酬的制度

③某地民政局免费为60岁以上的低保对象购买意外伤害保险

④某省给予社会办托老所的床位每张每月300元的财政补贴

A．①②　

B．①③　

C．②④　

D．③④
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