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从经济学理论上说，生产的外部不经济会造成( )。
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有限责任公司监事会中的职工代表的比例( )。
某企业利润总额为30000000元，利息费用为5000000元，所得税总额为10000000元，其他税金总额为3000000元，该企业的已获利息倍数是( )。
在关系数据模型中，通常可以把 (1) 称为属性，而把 (2) 称为关系模式。常用的关系运算是关系代数和 (3) 。在关系代数中，对一个关系作投影操作后，新关系的元组个数 (4) 原来关系的元组个数。
Psychologist George Spilich in Maryland College decided to find out whether, as many smokers say, smoking helps them to "think and concentrate". Spilich put young non-smokers, active smokers and smokers deprived(被剥夺) of cigarettes through a series of tests.In the first test, each subject(试验对象) sat before a computer screen and pressed a key as soon as he or she recognized a target letter among a group of 96. In this simple test, smokers, deprived smokers and nonsmokers performed equally well.The next test was more complex, requiring all to scan sequences of 20 identical letters and respond the instant one of the letters transformed into a different one. Non-smokers were the fast, but under the stimulation of nicotine(尼古丁), active smokers were faster than deprived smokers.In the third test of short-term memory, non-smokers made the fewest errors, but deprived smokers committed fewer errors than active smokers.The fourth test required people to read a passage, then answer questions about it. Nonsmokers remembered 19 percent more of the most important information than active smokers, and deprived smokers bested those who had smoked a cigarette just before testing. Active smokers tended not only to have poorer memories but also had trouble separating important information from insignificant details."As our tests became more complex," sums up Spilich, "non-smokers performed better than smokers by wider and wider margins. " He predicts, "smokers might perform adequately at many jobs until they got complicated. A smoking airline pilot could fly adequately if no problems arose, but if something went wrong, smoking might damage his mental capacity. \ Which of the following statement is true（）
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