In a democratic society citizens are encouraged to form their own opinions on candidates for public office, taxes, constitutional amendments, environmental concerns, foreign policy, and other issues. The opinions held by any population are shaped and manipulated by several factors: individual circumstances, the mass media, special-interest groups, and opinion leaders.
Wealthy people tend to think differently on social issues from poor people. Factory workers probably do not share the same views as white-collar, nonunion workers. Women employed outside their homes sometimes have perspectives different from those of full-time homemakers. In these and other ways individual status shapes one’s view of current events.
The mass media, especially television, are powerful influences on the way people think and act. Government officials note how mail from the public tends to "follow the headlines. " Whatever is featured in newspapers and magazines and on television attracts enough attention that people begin to inform themselves and to express opinions.
The mass media have also created larger audiences for government and a wider range of public issues than existed before. Prior to television and the national editions of newspapers, issues and candidates tended to remain localized. In Great Britain and West Germany, for example, elections to the national legislatures were usually viewed by voters as local contests. Today’s elections are seen as struggles between party leaders and programs. In the United States radio and television have been beneficial to the presidency. Since the days of Franklin D. Roosevelt and his "fireside chats," presidents have appealed directly to a national audience over the heads of Congress to advocate their programs.
Special-interest groups spend vast sums annually trying to influence public opinion. Public utilities, for instance, tried to sway public opinion in favor of nuclear power plants. Opposed to them were citizens’ organizations that lobbied to halt the use of nuclear power. During the 1960s the American Medical Association conducted an unsuccessful advertising campaign designed to prevent the passage of Medicare.
Opinion leaders are usually such prominent public figures as politicians, show-business personalities, and celebrity athletes. The opinions of these individuals, whether informed and intelligent or not, carry weight with some segments of the population. Some individuals, such as Nobel Prize winners, are suddenly thrust into public view by the media. By quickly reaching a large audience, their views gain a hearing and are perhaps influential in shaping views on complex issues.
It is obvious that the opinion of famous people（）
A.is often ignored by the public
B. is seldom expressed to the point
C. is often imposed on the public
D. has a p influence on people
由以上计算公式可知： (1)自振频率仅取决于体系本身的质量与刚度，与外界激发自由振动的因素无关。它是体系本身所固有的特性。 (2)单自由度体系的自振频率和刚度与质量比值的平方根成正比。刚度愈大或质量愈小，则自振频率愈高，反之，则愈低。因体系在动力作用下的响应与自振频率有关，所以在结构设计时可利用这种规律调整体系的自振频率，以达到减震的目的。 由此可知，本题应该选(B)。 [点评] 此题考察对单自由度体系自振频率概念的理解，考生不仅要掌握基本概念，还要求会计算简单的单自由度体系的自振频率。