控制性降压期间发生快速耐受性的原因有（） A.交感神经张力增加 B.血浆儿茶酚胺

Can I borrow your dictionary, please?           is at home.   [ ]

A. My                  

B. Me    

C. Mine                  

D. Myself

最大持续运行电压UC是选择（）三相配电系统中的电涌保护器（SPD）时的一项重要指标，TN制供电系统中安装的SPD的UC不应小于（）v。

对数据仓库特征的描述，（）是不正确的。

A.与时间无关的

B.不可修改的

C.面向主题的

D.集成的

已知2500个正常人血压的数据服从正态分布，计算出样本均值X和标准误s_x，求出区间（X-t_0.05，ν′S_x；+t_0.05，ν′S_x），该区间所代表的含义是（）

A.血压的99％正常范围

B.样本均值的95％波动范围

C.任何一个人血压的99％可信区间

D.总体均值的95％可信区间

E.以上都不是

FOR the past two years in Silicon Valley, the centre of America’s technology industry, conference-goers have entertained themselves playing a guessing game: how many times will a speaker mention the phrase "long tail" It is usually a high number, thanks to the influence of the long tail theory, which was first developed by Chris Anderson, the editor of Wired magazine, in an article in 2004. Though technologists and bloggers chuckle at how every business presentation now has to have its long-tail section, most are envious of Mr Anderson, whose brainwave quickly became the most fashionable business idea around.

Whether a blockbuster film, a bestselling novel, or a chart-topping rap song, popular culture idolizes the hit. Companies devote themselves to creating them because the cost of distribution and the limits of shelf space in physical shops mean that profitability depends on a high volume of sales. But around the beginning of this century a group of internet companies realized that with endless shelves and a national or even international audience online they could offer a huge range of products—and make money at the same time.

The niche, the obscure and the specialist, Mr Anderson argues, will gain ground at the expense of the hit. As evidence, he points to a drop in the number of companies that traditionally calculate their revenue/sales ratio according to the 80/20 rule—where the top fifth of products contribute four-fifths of revenues. Ecast, a San Francisco digital jukebox company, found that 98% of its 10,000 albums sold at least one track every three months. Expressed in the language of statistics, the experiences of Ecast and other companies such as Amazon, an online bookseller, suggest that products down in the long tail of a statistical distribution, added together, can be highly profitable. The internet helps people find their way to relatively obscure material with recommendations and reviews by other people and (for those willing to have their artistic tastes predicted by a piece of software) computer programs which analyze past selections.

Long-tail enthusiasts argue that the whole of culture will benefit, not just commercial enterprises. Television, film and music are such bewitching media in their own right that many people are quite happy to watch and listen to what the mainstream provides. But if individuals have the opportunity to pick better, more ideally suited entertainment from a far wider selection, they will take it, according to the theory of the long tail. Some analysts reckon that entire populations might become happier and wiser once they have access to thousands of documentaries, independent films and sub-genres of every kind of music, instead of being subjected to what Mr Anderson calls the tyranny of lowest-common-denominator fare. That might be taking things a bit far. But the long tail is certainly one of the internet’s better gifts to humanity.

With which of the following would the long-tail advocates most probably agree（）

A. People are more willing to catch what the mainstream provides

B. People have more opportunities to find entertainment through computer

C. People would be happy for having access to a wider selection

D. People in the cultural field benefit most from the long tail theory