Part 3
15.C
16-20 D A D B C

15.这一段主要讲在具体的市场之外发展出了一个抽象的市场，用来交易想法和知识。只有通过工作机会才能对知识进行交易。而只有工人提供自己的知识，才有可能进行交易，否则，别无他法。而工作量又是仅仅通过时间衡量的。通过这一句可以看出，因该选择C Opportunities to exploit your knowledge were limited in the past.其他选项在文中都没有提及。
16. But today the internet is making the distribution of knowledge ever easier. This is reducing the friction in the knowledge economy.从这两句可以看出应该选择D the internet facilitates the development of the knowledge economy.
17.Now you can sell your knowledge to newer, younger computer dealers who have no way to build up this knowledge without losing thousands of pounds finding it out the hard way. 从这一句可以看出选择A。
18.It’s a renewable resource. Better yet, its worth actually increases.从这句可以看出选择D Its value accumulates.
19.The value of knowledge often depends on variables such as time and the credibility of the seller.通过这一段可以看出选择B

introducing compatible parties.
20.通过最后一段可以看出选择C。