单选题Internet advertising is booming. The industry has gone from $ 9.6 billion in revenue in 2001 to $ 27 billion this year, according to Piper Jaffray, an investment bank. And it is still early days. The internet accounts for only 5% of total spending on advertising, but that figure is expected to reach at least 20% in the next few years. The single largest category within this flourishing industry, accounting for nearly half of all spending, is "pay-per-click" advertising, which is used by firms both large and small to promote their wares. The benefits of the pay-per-click approach over traditional advertising (television, radio, print and billboards are obvious. Since advertisers pay only to reach the small subset who actually respond to an advertisement, the quality of the leads generated is very high, and advertisers are prepared to pay accordingly. The price: per click varies from $ 0.10 to as much as $ 30, depending on the keyword, though the average is around $ 0.50. Google made most of its $ 6.1 billion in revenue last year from pay-per-click advertising. But as pay-per-click advertising has grown into a huge industry, concern has mounted over so-called "click fraud"--bogus clicks that do not come from genuinely interested customers. It takes two main forms. If you click repeatedly on the advertisements on your own website, or get other people or machines to do so on your behalf, you can generate a stream of bogus commissions. Click fraud can also be used by one company against another: clicking on a rival firm's advertisements can saddle it with a huge bill. Bogus clicks are thought to account for around 10% of all click traffic, though nobody knows for sure. A few months ago Mr. Gross pioneered an alternative to the pay-per-click model. In February, Snap, a search engine backed by Mr. Gross, launched "pay-per-action" (PPA), a new model in which advertisers pay only if a click on an ad is followed by an action such as a purchase or a download. Might this put an end to click fraud? Don't bet on it, says Mike Zeman at Starcom, an advertising agency. Payper-action will be a niche, he predicts, since converting a click into an action depends on a variety of factors such as the ease of use of the advertiser's website. Google and its peers will be reluctant to be so dependent on factors outside their control. But Mr. Tobaccowala thinks pay-per-action could become a real alternative to pay-per-click. As bigger companies spend more on internet advertising; they will demand more accountability and a wider range of options, he says. At the very least, that means clamping down on click fraud; but it also presents an opportunity for entrepreneurs to invent new models that are less vulnerable to abuse.

单选题A、慢支 B、支气管哮喘 C、肺TB D、支气管扩张 E、肺癌

单选题男性，31岁，因发作性高血压伴头痛、心悸入院，血压最高时210／140mmHg，诊断为嗜铬细胞瘤，宜选择下列哪种药物做术前准备

单选题在风湿性心脏病联合瓣膜病中，以下哪项组合最常见

单选题关于急进型高血压的叙述，错误的是

单选题急性轻型肝炎的病变特点是

单选题A．扑翼样震颤无法引出B．轻度性格改变和行为失常C．昏睡和精神错乱D．意识错乱和睡眠倒错

单选题下列哪项不引起高排血量心力衰竭

单选题引起婴幼儿急性胃肠炎的主要病原体是

单选题不符合溃疡型胃癌的描述是

单选题下列哪项符合稳定型心绞痛的特点

单选题A．心房颤动 B．心力衰竭 C．乳头肌功能失调 D．胸腔积液

单选题女，58岁，咳嗽，咳血丝痰1个月，有低热及右胸痛，X线示右胸中等量积液。胸腔穿刺液检查示：淡红色，比重1．018，蛋白30g／L，细胞数0．5×10 9 ／L，ADA 35U／L，CEA 2％g／L，胸液未找到癌细胞及抗酸杆菌。最应考虑的是

单选题女性，27岁，反复口腔溃疡1年，近2个月自觉畏光、流泪，伴四肢结节性红斑，化验ANA(-)，皮肤针刺反应阳性，考虑可能的诊断是

单选题男性患者，33岁，反复上呼吸道感染时尿中泡沫增多4个月，颜面、眼睑、双下肢无浮肿，血压120／75mmHg，多次24小时尿蛋白定量0．76～0．92g，尿蛋白圆盘电泳以中分子带为主，肌酐、尿素氮均正常，诊断隐匿性肾炎。蛋白尿应是

单选题高血压治疗原则，除外下列哪项

单选题慢性支气管炎、肺气肿患者，血气分析结果为pH7.38、PaCO 2 10.8kPa，给予吸氧后，PaO 2 维持多少较为合适

单选题 男性，18岁，诊断为风湿性心脏病主动脉关闭不全，下列哪项不是周围血管征? A、随心脏搏动的点头征 B、水冲脉 C、枪击音 D、毛细血管搏动征 E、奇脉

单选题下述各种原因引起的脾大中，最易发生脾功能亢进的是

单选题抗甲状腺药物治疗甲亢时开始发挥作用的时间是