The fact that most Americans live in urban areas does not mean that they reside in the center of large cities. In fact, more Americans live in the suburbs of large metropolitan areas than in the cities themselves.
The Bureau of the Census regards any area with more than 2,500 people as an urban area, and does not consider boundaries of cities and suburbs.
According to the Bureau, the political boundaries are less significant than the social and economic relationships and the transportation and communication systems that integrate a locale. The term used by the Bureau for an integrated metropolis is an MSA, which stands for Metropolitan Statistical Area. In general, an MSA is any area that contains a city and its surrounding suburbs and has a total population of 50,000 or more.At the present time, the Bureau reports more than 280 MSAs, which together account for 75 percent of the US population. In addition, the Bureau recognizes 18 megapolises, that is, continuous adjacent metropolitan areas. One of the most obvious megapolises includes a chain of hundreds of cities and suburbs across 10 states on the East Coast from Massachusetts to Virginia, including Boston, New York, and Washington, D.C. In the Eastern Corridor, as it is called, a population of 45 million inhabitants is concentrated. Another megapolis that is growing rapidly is the California coast from San Francisco through Los Angeles to San Diego.
Which of the following are NOT considered important in defining an urban area().
A. Political boundaries.
B. Transportation networks.
C. Social relationships.
D. Economic systems.
按要求对此工作表完成如下操作并原名保存： (1)打开工作簿文件EXCEL.XLS，将下列某市老年人占全市人口的比例情况数据建成一个数据表(存放在A1:D5的区域内)，并求出“老龄化比率”(保留小数点后面两位)，其计算公式是：老年人数/全市人数二老龄化比率，其数据表保存在Sheet1工作表中。 时间 全市人数(万) 老年人数(万) 老龄化比率 1994245 88 1995353 112 1996450 199 1997612 267 (2)选“时间”和“老龄化比中”两列数据，创建“柱形棱锥图”图表，设置分类(x)轴为“时间”，数值(Y)轴为“老龄化比率”，图表标题为“某市老龄化比率”，嵌入在工作表A8:F17的区域中。