The two most obvious changes in American economy are the emergence of a highly sophist

icated technology and the rise of giant corporations.In addition, market forces have lost some of their significance as planning has become more important.The government has assumed a greatly changed role in the economy.Property relationships and decision-making power have shifted.The demand for highly educated specialists has increased enormously.

We may think of the American economy, as consisting of two completely different sectors.The world of the giant corporations, which can be called the "industrial system", consists of 500 or 600 firms that provide "nearly all communications, nearly all production and distribution of electric power, much transportation, most manufacturing and mining, a substantial share of retail trade, and a considerable amount of entertainment." Outside of this industrial system fall most agricultural enterprises, some mining and trucking, professional and artistic pursuits, some retail trade, and most personal and domestic services.

The classical economic laws of supply and demand still apply to some degree.But today the industrial sector is characterized far more by planning and certainty than by the free play of market forces.It appears that it could scarcely be otherwise.In large corporations with advanced technological systems and complex organizations of highly trained specialists, plans for producing any one item are made well in advance.Such plans, once made, are hard to change.Because long-term planning demands certainty, market forces are avoided by various means.For example, the corporation may achieve "vertical integration" by buying companies that supply raw materials at one end of the process and distribution outlets at the other.Corporations may agree on "just prices" for things they buy and sell.They may enter mutually advantageous long-term contracts with suppliers and customers.Moreover, in their quest for certainty they generally have the support of the state.

26.The American giant corporations possess so many new characteristics that

A) highly educated managers are important for the corporations

B giant corporations become decentralized

C economic laws of the market are effective inside corporations

D heads of the giant corporations try to control the government

27.By the second paragraph, we know that .

A retail trade accounts for a big part in non-industrial system

B there are more giant corporations than agricultural enterprises

C giant corporations control every part of American economy

D giant corporations provide most of productions and services

28.From the whole passage, we can infer that American economy .

A is experiencing the rise of giant corporations

B is determined by hundreds of giant corporations

C has failed to balance supply and demand

D becomes highly-planned one

29.In the third sentence of last paragraph, the second "it" may refer to.

A classic economic law of supply and demand

B industrial sector

C American economy

D market force

30.Which of the following is not mentioned in the passage？

A American economy is characterized by high technology and giant corporations.

B American economy consists of industrial systems and agricultural enterprises.

C.Market economy is gradually replaced by planned economy.

D Highly trained specialists are needed.