[单项选择]It is difficult ______ a world record and even more difficult to ______ it.
A. keeping, set
B. keep, set
C. set, keep
D. to set, keep

[单项选择]It is difficult ______ a world record and even more difficult to ______ it.
A. keeping, set
B. keep, set
C. set, keep
D. to set, keep

[单项选择]It is difficult （　）a world record and even more difficult to （　） it.
A. keeping, set
B. keep, set
C. set, keep
D. to set, keep

[单项选择]It is difficult ______a world record and even more difficult to ______it.
A. keeping, set
B. keep, set
C. set, keep
D. to set, keep

[单项选择]The president's fitful rule is seen to be even more de signed to serve the interests of people ______.


A. at a loss
B. at a stroke
C. at large
D. at hand

[单项选择]It is difficult to conceive how, even for those people well disposed to rule themselves, the attempt to achieve happiness should be rendered so ------- by one single curse, that of a bad form of government.


A. laudatory
B. ineffectual
C. corrupt
D. disorganized
E. (E) ill-tempered

[单项选择]It will be even more difficult to develop a vaccine because______.


A. most women are infected by a single variant of the HIV virus
B. the virus can duplicate itself into more genetic variants
C. it is difficult to monitor the activities of the viruses
D. technologies are not advanced now

[单项选择]An unauthorized biography is likely to attract more readers because ______.

[单项选择]An unauthorised biography is likely to attract more readers because______.

[单项选择]The fact（　） English and computers are becoming more and more important in our daily life is known to us all.
A. That
B. which
C. as
D. / (不填)

[单项选择]According to this passage, deep dream sleep is more likely to occur in ______.


A. flies
B. vulnerable birds
C. puppies
D. tigers

[单项选择]As ordinary people, scientists are by no means more honest or _______ than other people, but as scientist, they attach special value to honest while they are in their working sphere.
A. ethical
B. ethnic
C. aesthetic
D. esthetic

[单项选择]

Text 4
Adam Smith, the Scottish professor of moral philosophy, was thrilled by his recognition of order in the economic system. His book, the Wealth of Nations (1776), is the germinal book in the field of economics which earned him the title "the father of economics".
In Smith’s view, a nation’s wealth was dependent upon production, not agriculture alone. How much it produced, he believed, depended upon how well it combined labor and the other factors of production. The more efficient the combination, the greater the output, and the greater the nation’s wealth.
The essence of Smith’s economic philosophy was his belief that an economy would work best if left to function on its own without government regulation. In those circumstances, self-interest would lead business firms to produce only those products that consumers wanted, and to produce them at the lowest possible cost. They would do this, not as a means of bene
A. an efficiency allocation of resources can only be achieved in a free market.
B. perfect competition can be realized in a free market.
C. self-interest can help to maximize production and minimize inputs.
D. monopolies sometimes can help accelerate the development of a free market.