阅读理解专项训练（12）

Public goods are those commodities from whose enjoyment nobody can be effectively excluded．Everybody is free to enjoy the benefits of　these commodities，and one person's utilization does not reduce the possibilities of anybody else's enjoying the same good．

Examples of public goods are not as rare as one might expect．A flood controlled dam is a public good．Once the dam is built，all persons living in the area will benefit—irrespective of their own contribution to the construction cost of the dam．The same holds true for highway signs or aids to navigation．Once a lighthouse is built，no ship of any nationality can be effectively excluded from the utilization of the lighthouse for navigational purposes．National defense is another example．Even a person who voted against military expenditures or did not pay any taxes will benefit from the protection afforded．

It is no easy task to determine the social costs and social benefits associated with a public good．There is no practicable way of charging drivers for looking at highway signs，sailors of watching a lighthouse，and citizens for the security provided to them through national defense．Because the market does not provide the necessary signals，economic analysis has to be substituted for the impersonal judgment of the marketplace．

1．With what topic is the passage mainly concerned？

A）Mechanisms for safer navigation．

B）The economic structure of the marketplace．

C）A specific group of commodities．

D）The advantages of lowering taxes．

2．Which of the following would NOT be an example of a public good as described in the passage？

A）A taxicab．B）A bridge． C）A fire truck．D）A stoplight．

3．In line 8，the word“holds”can best be replaced by which of the following？

A）Has．B）Is．C）Grasps．D）Carries．

4．According to the passage，finding out the social costs of a public good is a_________．

A）difficult procedure B）daily administrative duty

C）matter of personal judgment D）citizen's responsibility

5．Which of the following statements best describes the organization of the first two paragraphs？

A）Suggestions for the application of an economic concept are offered．

B）Several generalizations are presented from which various conclusions are drawn．

C）Persuasive language is used to argue against popular idea．

D）A general concept is defined and then examples are given．

6．Put the underlined sentence in the first paragraph into Chinese．

参考答案：CABAD

翻译：每个人都可以自由享受这些商品的益处，而且一个人的享用不会减小别人享受同一好处的可能性。