The average age of chief executive officers(CEOs)in a large sample of companies is The average age of CEOs in those same companies 20 years ago was approximately eight years younger. On the basis of those data, it can be concluded that CEOs in general tend to be older now. Which of the following casts the most doubt on the conclusion drawn above？
A. The dates when the CEOs assumed their current positions have not been specified.
B. No information is given concerning the average number of years that CEOs remain in office.
C. The information is based only on companies that have been operating for at least 20 years.
D. Only approximate information is given concerning the average age of the CEOs 20 years ago.
E. Information concerning the exact number of companies in the sample has not been given.
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Extraordinarily few people have the ability to be successful commodity traders. So rather
A. Over the past decade, Quinsey-Leerheim"s trading practices and policies have changed in a way that gives much more responsibility to individual traders.
B. Since the pool of entry-level applicants is mostly the same for all commodity-trading firms, Quinsey-Leerheim often competes with other trading firms for the strongest applicants.
C. Quinsey-Leerheim rejects some entry-level applicants who go on to become extremely successful commodity traders with other trading firms.
D. Commodity trading requires skills that are needed in very few other occupations, so that trading firms" hiring procedures typically differ significantly from those of other financial firms.
E. Commodity trading is very stressful, and even successful commodity traders rarely work as traders for longer than ten years, although they often earn substantial sums in those years.
港口制定的作业技术标准，又称_______。
A. 港口装卸规程
B. 港口装卸标准
C. 装卸工艺
D. 装卸工艺标准转自学易网
产品的概念包含核心产品、形体产品和延伸产品三项内容。()
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