When choices are made among alternatives such as those just described, it becomes plain that choosing one alternative often involves giving up another. For example, suppose you go to classes 4 hours a day and get 8 hours of sleep. You will have an additional 12 waking hours to allocate per day. Suppose now that the only other activities you view as worth pursuing are watching TV and studying. If you choose to watch TV for 12 hours a day, no time will be left for studying, assuming you continue to sleep for 8 hours in each 24-hour period and do not cut classes. If you choose each day to devote 6 hours to studying, only 6 of the 12 waking hours will be available for watching TV. You must give up the opportunity of watching more hours of TV in the process of choosing to study. We can therefore say that the decision to study costs you 6 hours of TV watching.
Economists use the term "opportunity cost" to mean the cost of a specific choice measured in terms of the next best alternative choice. In other words, it is what the decision maker must forego in order to make the choice that is finally made. Thus, in our example, the opportunity cost of studying for 6 hours was 6 hours of watching TV. We can see many other examples of opportunity costs around us. For example, governments are faced with limited budgets and therefore with limited resources that can be used to provide goods and services to citizens. If a government chooses to improve its military forces, it may well do so by allocating fewer resources for libraries or schools. The opportunity cost of a strong defense may be a reduction in the size of library holdings or educational services.
26. What is most probably the key point discussed immediately before this passage?
[A] Limited time. [B] Making choices.
[C] Opportunity cost. [D] The shortage of resources.
27. According to the passage, choices must be made because ______.
[A] resources are abundant
[B] there is too much for us to do
[C] there are only 24 waking hours in a day
[D] our means are limited, but our wants are unlimited
28. According to the passage, economists define "opportunity cost" as "_______".
[A] an opportunity given up in terms of cash
[B] the cost of a better choice measured in terms of cash :
[C] giving up a specific choice for the next best alternative
[D] the cost of a specific choice measured in terms of any alternative choice
29. In the examples cited in the passage, the opportunity cost of studying for 4 hours per day was_____.
[A] 4 hours of watching TV [B] 4 hours of classes
[C] 4 hours of sleep [D] 8 hours of sleep
30. If a government chooses to allocate more of its resources to its military forces, there is a possibility of reduction in resources allocated for _____.
[A] libraries and education [B] libraries and business firms
[C] education and business firms [D] libraries, business firms and education
Passage Three
Questions 31 to 35 are based on the following passage.
Going online is a favorite recreation for millions of American children. Almost 10 million (14 percent) of America\'s 69 million children are online. The Internet both entertains and educates children, however, there are some possible negative consequences for children who access kid-based Web sites. Advertising on kid-based Web sites has become both a rapidly growing market for consumer companies and a concern for parents. With a click on an icon, children can link to advertisers and be granted tremendous spending power. Children are an important target group for consumer companies. Children under age 12 spent $ 14 billion, teenagers another $ 67 billion, and together they influenced $ 160 billion of their parents\' incomes.
Many critics question the appropriateness of targeting children in Internet advertising and press to require that children be treated as a "special case" by advertisers. Because children lack the analytical (分析的) abilities and judgment of adults, they may be unable to evaluate the accuracy of information they view, or understand that the information they provide to advertisers is really just data collecte
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