单选题
Public goods are those commodities from whose
enjoyment nobody can be{{U}} {{U}} 1 {{/U}} {{/U}}excluded.
Everybody is free to{{U}} {{U}} 2 {{/U}} {{/U}}the benefits of
these commodities, and one person's utilization {{U}} {{U}} 3
{{/U}} {{/U}}the possibilities of anybody else's enjoying the same goods.
Examples of public goods are not{{U}} {{U}}
4 {{/U}} {{/U}}one might expect. A flood control dam is a public goods.
Once the dam is built, all the people living in the area will benefit{{U}}
{{U}} 5 {{/U}} {{/U}}their own contribution to the construction cost
of the dam. The same{{U}} {{U}} 6 {{/U}} {{/U}}true for highway
signs or aids to navigations. Once a lighthouse is built, no ship of any
nationality can be effectively excluded from the{{U}} {{U}} 7
{{/U}} {{/U}}the lighthouse for navigational purposes. National defense is
another example. Even a person who voted against military expenditures
or{{U}} {{U}} 8 {{/U}} {{/U}}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{{U}} {{U}} 9 {{/U}} {{/U}}drivers for 100 at
highway signs, sailors for watching a lighthouse, and citizens for the security
provided to them through national defense. {{U}} {{U}} 10
{{/U}} {{/U}}the market does not provide the necessary signals, economic
analysis has to be substituted for the impersonal judgment of the market
place.
【答案解析】[解析] B项enjoy意为“享有”。因下文为the benefits of these commodities，所以若选A项，则为have the benefits，“有……益处”。C项concern有一个固定短语：be concerned with sth．“关心，关注某事。”D项contribute“捐献，贡献。”
单选题
A. will reduce
B. will enhance
C. does not reduce
D. does not exclude
【正确答案】
C
【答案解析】[解析] does not reduce意为“不降低”。讲一般道理时用一般现在时。而且，据上下文意思“一个人利用这些公共商品不应降低其他人利用它们的可能性”来判断，C项才是正确答案。
单选题
A. as same as
B. as rare as
C. as far as
D. as good as
【正确答案】
B
【答案解析】[解析] 此句是要举例说明公共商品的享有。作者用not as rare as one might expect来表示有很多这类例子。