化学课上教师为培养学生探究能力，让学生对一包干燥的白色粉末组成进行探究．请你参与并回答有关问题：

【教师提醒】它由碳酸钙、碳酸钠、氢氧化钠三种固体中的一种或两种组成．

【提出猜想】白色粉末可能的组成有：①只有碳酸钙；②只有碳酸钠；③只有氢氧化钠；④是碳酸钠、碳酸钙的混合物；⑤是碳酸钙、氢氧化钠的混合物；⑥是______的混合物．

【实验探究】（1）甲同学取适量白色粉末装入试管中，然后加入足量的水，振荡．结果白色粉末全部溶解，从而排除猜想中的______（填猜想中的序号），理由是______．

（2）在甲同学实验结论的基础上，乙同学另取少量白色粉末于试管中，加入足量的水溶解后再滴加2～3滴酚酞试液，振荡后观察，溶液变成红色．乙同学认为只有猜想③正确，可是丙同学却不是这样认为，他的理由是______．

（3）丁同学进一步确定白色粉末的组成，在甲同学所得的溶液中加入足量的稀硫酸，结果有气泡产生，于是丁同学认为可以排除猜想③，试写出产生气体的反应的化学方程式：______．

【交流讨论】

通过上述实验探究，小组内展开了激烈的讨论，有的同学认为猜想②正确，有的同学认为自已的猜想⑥正确，各执一词．于是小明同学想出一种方法：______

．

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)

12（）

A.personnel

B.locality

C.natives

D.individuals