被称为计算机之父的是（）。 A.图灵 B.比尔，盖茨 C.冯.诺依曼 D.巴贝奇

数据库系统中可能会发生各种各样的故障。这些故障主要有四类，即：事务故障、系统故障、介质故障和 ______ 。

流入电路中一个节点的电流之和（）流出该节点的电流之和。

A.大于

B.小于

C.等于

D.无关。

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.

有机纤维类材料燃烧时一般采用下列哪种灭火方法（）

A、用1211灭火机灭火

B、用黄砂

C、CO₂灭火机

D、四氯化碳

移动电容式传感器动极板，导致两极板有效覆盖面积A发生变化的同时，将导致电容量变化，传感器电容改变量ΔC与动极板水平位移成线性关系、与动极板角位移成（）关系。