Answer the following questions (简答题)What are the differences among needs, wants and demands?
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Define the following terms in your own words. (名词解释)licensing
Define the following terms in your own words. (名词解释)oligopoly
试验设计的基本原则()
A. 重复
B. 均匀试验
C. 局部控制
D. 随机排列
相关系数是用于描述变量x与y的线性相关程度的,常用r来表示,如果r=±1,则表明x与y没有线性关系;如果r≈0,则表明x与y之间存在精确的线性关系。