SQL语言中对权限回收的命令是()。

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问题:

SQL语言中对权限回收的命令是()。

考点:计算机等级考试数据库技术全国计算机等级考试三级数据库技术真题2004年4月
题型:填空题
理想变压器原线圈接在如图所示的电压上,原副线圈匝数之比为10:1,串在原线圈上的电流表的示数为1A,则以下叙述正确的是(  )

A.变压器输出功率为200W

B.若n1=100匝,则输出端线圈的磁通量变化率的最大值为2Wb/s

C.副线圈两端的电压表示数20V

D.变压器的输入功率是由发电厂的输出功率决定的

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阅读理解。

     Increasingly, Americans are becoming their own doctors, by going online to diagnose their symptoms,

order home health tests or medical devices, or even self-treat their illnesses with drugs from Internet

pharmacies (药店). Some avoid doctors because of the high cost of medical care, especially if they lack

health insurance. Or they may stay because they find it embarrassing to discuss their weight, alcohol

consumption or couch potato habits. Patients may also fear what they might learn about their health, or

they distrust physicians because of negative experiences in the past. But playing doctor can also be a deadly

game.

     Every day, more than six million Americans turn to the Internet for medical answers-most of them

aren't nearly skeptical enough of what they find. A 2002 survey by the Pew Internet & American Life Project

found that 72 percent of those surveyed believe all or most of what they read on health websites. They

shouldn't. Look up "headache", and the chances of finding reliable and complete information, free from a

motivation for commercial gain, are only one in ten, reports an April 2005 Brown Medical School study. Of

the 169 websites the researchers rated, only 16 scored as "high quality". Recent studies found faulty facts

about all sorts of other disorders, causing one research team to warn that a large amount of incomplete,

inaccurate and even dangerous information exists on the Internet.

     The problem is most people don't know the safe way to surf the Web. "They use a search engine like

Google, get 18 trillion choices and start clicking. But that's risky, because almost anybody can put up a site

that looks authoritative (权威的), so it'd hard to know if what you're reading is reasonable or not," says Dr.

Sarah Bass from the National Cancer Institute.

1. According to the text, an increasing number of American _____.

A. are suffering from mental disorders

B. turn to Internet pharmacies for help

C. like to play deadly games with doctors

D. are skeptical about surfing medical websites

2. Some Americans stay away from doctors because they _____.

A. find medical devices easy to operate

B. prefer to be diagnosed online by doctors

C. are afraid to face the truth of their health

D. are afraid to misuse their health insurance

3. According to the study of Brown Medical School, ______.

A. more than 6 million Americans distrust doctors

B. only 1/10 of medical websites aim to make a profit

C. about 1/10 of the websites surveyed are of high quality

D. 72% of health websites offer incomplete and faulty facts

4. Which of the following is the author's main argument?

A. It's cheap to self-treat your own illness.

B. It's embarrassing to discuss your bad habits.

C. It's reasonable to put up a medical website.

D. It's dangerous to be your own doctor.

题型:填空题

急性肾小球肾炎的诊断根据中哪一项是关键()

A.高血压

B.全身水肿

C.尿少

D.血尿及红细胞管型尿

E.蛋白尿及透明管型尿

题型:填空题

让刀是指铣削台阶时,铣刀容易向不受力的一侧偏让。

题型:填空题

明朝为了便于对长城全线的管理和修筑,将全线分为九镇,以下不属于这九个镇的是()

A.辽东镇

B.延绥镇

C.辽西镇

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