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问题 选择题

A、B、C均为短周期元素，它们在周期表中的位置如右下图。已知B、C两元素在周期表中族序数之和是A元素族序数的2倍；B、C元素的原子序数之和是A元素原子序数的4倍，则A、B、C分别是（   ）

A．Be  Na  Al                  B．B  Mg  Si

C．O  P  Cl                    D．C  Al  P

答案

答案：C

题目分析：设A的原子序数为，则B、C的原子序数分别为，可得关系式，解得，因此A为氧元素、B为P、C为Cl。故答案选C。

点评：对元素周期表中元素位置的确定，属于基础内容，本题解答的关键在于明确各元素的相关位置以及与其相邻的元素的原子序数关系。同时，需熟记前20号元素。

问答题 简答题

目前全世界出生缺陷的状况如何？
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单项选择题

Jack’s friend Tony had recently gotten a tattoo (纹身), and Jack was so impressed by Tony’s bravery and his tattoo that he decided to get one too. Why do a lot of young people in North America get tattoos today Peer pressure, media influence, and personal expression are some of the common reasons.
The desire to be part of a group, to be accepted by one’s friends or peers, can have a great influence on what a person does. Sometimes, wearing a tattoo can be a sign that you belong to a certain group. Gangs often use special clothes and tattoos to identify their particular group. For example, in one gang all the members may wear green army jackets and have large "Xs" tattooed on their arms. It is not only gangs that have this type of special "uniform". Young people often belong to a certain group of friends. Some of these groups wear only brand-name clothes. Others wear tattoos. When a person’s friends are all doing something, such as getting a tattoo, that person is more likely to do the same thing, and get a tattoo too.
The media is another big influence behind the popularity of tattoos in North America. A wide variety of media images show tattoos. Tattoos can be seen on people appearing in commercials selling expensive cars. Famous sports heroes with tattoos are shown in magazines. Fashion models are often seen in magazines and on TV wearing designer clothes that show their bodies tattooed with detailed and colorful patterns. These media images link tattoos to ideas of wealth, success, and status. As a result, many people decide to get a tattoo for its fashion and status value.
It is not always the influence of other people or the media that results in a person getting a tattoo. Many people decide to wear tattoos in order to express their artistic nature, their beliefs, or their feelings -- in other words, to show their individuality. A musician in a rock band may get a tattoo of a guitar on the arm. Some environmentalists may tattoo pictures of endangered animals on their shoulders. Lovers may tattoo each others’ names over their hearts. A tattoo can be a public sign to show what is important in a person’s life.

Which of the following groups of people are seen wearing tattoos in the media

A. Sports Stars.
B. Car sellers.
C. Fashion designers.
D. Movie stars.
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