In a market system, individual economic units are free to interact among each other in the marketplace. It is possible to buy commodities from other economic units or sell commodities to them. In a market, transactions may take place via barter or money exchange. In a barter economy, real goods such as automobiles, shoes, and pizzas are traded against each other. Obviously, finding some body who wants to trade my old car in exchange for a sailboat may not always be an easy task. Hence, the introduction of money as a medium of exchange eases transactions considerably. In the modern market economy, goods and services are bought or sold for money.In the following paragraph, the word “ real goods” could best be replaced by which of the following?
A. High quality
B. Concrete
C. Utter
D. Authentic
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Social support cushions stress in a number of ways. First, friends, relatives, and co-workers may let us know that they value us. Our self-respect is strengthened when we feel despite our faults and difficulties. Second, other people often provide us with informational support. They help us to define and understand our problems and find solutions to them. Third, we typically find social companionship supportive. Engaging in leisure-time activities with others helps us to meet our social needs while at the same time distracting (转移…注意力) us from our worries and troubles. Finally, other people may give us instrumental support—financial aid, material resources, and needed services—that reduces stress by helping us resolve and cope with our problems.Which of the following is closest in meaning to the word “cushions”?
Adds up to.
B. Does away with.
C. Lessens the effect of.
D. Lays the foundation for.
President Coolidge’s statement, “ The business of America is business” still points to an important truth today—that business institutions have more prestige in American society than any other kind of organization, including the government. Why do business institutions possess this prestige?The statement “ The business of America is business” probably means____.
A. the business institutions in America are concerned with commerce
B. business problems are of great importance to the American government
C. business is of primary concern to Americans
D. America is a great power in world business
下列哪项不是流行病学实验设计的原则
A. 设立对照的原则
B. 随机化的原则
C. 重复测量的原则
D. 盲法的原则
下列哪项试验不属于流行病学实验研究
A. 观察性试验
B. 社区试验
C. 现场试验
D. 临床试验