题目内容
设关系模式R＜U，F＞，其中U＝{A，B，C，D，E}，F＝{A→BC，C→D，BC→ E，E→A}，则分解ρ＝{R1(ABCE)，R2(CD)}满足(43)。
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Which group of women spent less time online than men？
Traditionally, women have lagged behind men in adoption of Internet technologies, but a study released yesterday found that women under age 65 now outpace men in Internet usage. The report, "How Women and Men Use the Internet," examined use by both sexes, looking at what men and women are doing online as well as their rate of adopting new Web-based technologies. "I think the real interesting story is the young women, because that is the one age cohort where there are many more women online," said Deborah Fallows, who wrote the report based on findings from surveys conducted over the past five years. "The younger women are just much more comfortable with the Internet." The report found that 86 percent of women ages 18 to 29 were online, compared with 80 percent of men in the same age group. Among African Americans, 60 percent of women are online, compared with 50 percent of men.
In other age groups, the disparity is only slight, with women outpacing men by 3 percentage points. However, among the older group, those age 65 and older, 34 percent of men are online, compared with 21 percent of women. It's enough of a disparity, Fallows said, to keep men in the overall lead in Internet usage, 68 percent to 66 percent. Men tend to use the Web for information and entertainment--getting sports scores and stock quotes and downloading music--while women tend to be heavier users of mapping and direction services, and communication services such as e-mail. And, in general, men are more likely to be early adopters of technology than women, the survey found.
A separate survey released earlier this week seemed to underscore the finding of the report. Of those who listen to podcasts distributed over the Internet, 78 percent are men and 22 percent are women. "With podcasting just over a year old, the current maleness of the podcast audience at the aggregate level is consistent with gender usage trends of the early Web." Mark McCrery, cofounder and chief executive of Podtrac, said in a statement. Over time, however, there likely will be "a more balanced gender composition of the podcast audience," he said. Fallows agreed but also said that the disparity between the sexes among younger people was especially interesting because it could shape the way the general population uses technology and the Web in the future. "It's hard to say where that will settle," she said. "I imagine things will even out over time, because there is so much for everyone online."
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Which one can help improve doctor's prescribing controlled drugs according to the passage？
According to the author what should be blamed for teenagers' abusing controlled ______ substance？
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