两组学龄前儿童,一组儿童有龋病,另一组儿童无龋病。通过一些临床检查和问卷调查获得有关

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问题:

两组学龄前儿童,一组儿童有龋病,另一组儿童无龋病。通过一些临床检查和问卷调查获得有关资料后分析龋病的病因,这种研究方法是

A.纵向研究

B.横断面研究

C.常规资料分析

D.病例对照研究

E.队列研究

考点:口腔执业医师口腔执业医师10
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为了阻止利益的冲突,国会可以限制高级政府官员在离开政府后的3年内接受说客的职位。然而一位官员断言,这个限制是不幸的,因为它将阻断高级官员3年的谋生之道。这位政府官员的结论逻辑地依靠以下哪条假设

A.法律不应限制前政府官员的行为。
B.说客主要由曾在政府担任高级官员的人来担任。
C.政府的低级官员离开政府后不经常担任说客。
D.高级官员离开政府后只能以说客谋生。
E.现在高级官员离开政府只允许做3年说客。

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The girls in this sixth grade class in East Palo Alto, California, all have the same access to computers as boys. But researchers say, by the time they get to high school, they are victims of what the researchers call a major new gender (性别) gap in technology. Janice Weinman of the American Association of University Women says, "Girls tend to be less comfortable than boys with the computer. They use it more for word processing rather than for problem solving, rather than to discover new ways in which to understand information."

The gender gap needs to be closed because ______.
A. it isn’t fair that boys are allowed to use computers all the time
B. there isn’t enough money for upgrading computers
C. most of the causes may boil down to a question of money
D. the ability to use computers is important in today’s world

After re-examining a thousand studies, the American Association of University Women researchers found that girls make up only a small percentage of students in computer science classes. Girls consistently rate themselves significantly lower than boys in their ability and confidence in using computers. And they use computers less often than boys outside the classroom.An instructor of a computer lab says he’s already noticed some differences. Charles Cheadle of Cesar Chavez School says, "Boys are not so afraid they might do something that will harm the computer, whereas girls are afraid they might break it somehow."
Six years ago, the software company Purple Moon noticed that girls’ computer usage was falling behind boys. Karen Gould says, "The number one reason girls told us they don’t like computer games is not that they’re too violent, or too competitive. Girls just said they’re incredibly boring."
Purple Moon says it found what girls want, characters they can relate to and story lines relative to what’s going on in their own lives. Karen Gould of Purple Moon Software says, "What we definitely found from girls is that there is no intrinsic (固有的) reason why they wouldn’t want to play on a computer; it was just a content thing."
The sponsor of the study says it all boils down to this: the technology gender gap that separates the girls from the boys must be closed if women are to compete effectively with men in the 21st century.

题型:单项选择题

TCP/IP () layer protocols provide services to the application () running on a computer. The application layer does not define the application itself, but rather it defines () that applications need—like the ability to transfer a file in the case of HTTP. In short, the application layer provides an () between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP () layer consists of two main protocol options—the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

but rather it defines () that applications need—like the ability to transfer a file in the case of HTTP.

A.services

B.processes

C.applications

D.address

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硫酸氢钠(NaHSO4)在水溶液中能解离出钠离子、氢离子与硫酸根离子,则与下列物质①Zn,②NaOH溶液,③BaCl2溶液,④CO2,能发生反应的组合是(  )

A.③

B.①②③④

C.①②③

D.②③

题型:单项选择题

在道路上发生交通事故造成人身伤亡时,要立即抢救受伤人员并迅速报警。

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