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阅读下面的科技文,完成后面的问题。

指纹的特性和用途

人的皮肤由表皮、真皮和皮下组织三部分组成。指纹就是表皮上突起的纹线。由于人的遗传特性,虽然指纹人人皆有,但各不相同。伸出你的手,仔细观察,就可以发现小小的指纹也分好几种类型:有同心圆或螺旋纹线,看上去像水中漩涡的,叫斗形纹;有的纹线是一边开口的,就像簸箕似的,叫箕形纹;有的纹形像弓一样,叫弓线纹。各人的指纹除形状不同之外,纹形的多少、长短也不同。据说,全世界五十多亿人中,还没有发现两个指纹完全相同的人呢。更有趣的是,指纹在胎儿第三四个月便开始产生,到六个月左右就形成了。当婴儿长大成人,指纹也只不过放大增粗,它的形状特征却固定不变。

你可别小看指纹,它的用途可大啦!指纹由皮肤上许多小颗粒排列组成,这些小颗粒感觉非常敏锐,只要用手触摸物体,它就会立即把感觉到的冷、热、软、硬等各种“情报”通报给大脑这个司令部,然后,大脑根据这些“情报”发号施令,指挥动作。指纹还具有增强皮肤摩擦的作用,使手指能紧紧地握住东西,不易滑掉。我们平时画图、写字、拿工具、做手工,之所以能够那么得心应手,运用自如,这里面就有指纹的功劳。

正因为指纹的这些特征,它很早就引起人们的兴趣。在古代,人们把指纹当做“图章”,印在公文上。

据说,在一百多年前,警察就开始利用指纹破案。

(A)现在,随着科学技术的发展,

(B)指纹在医学上又有了新的用途。有的医生发现,通过检查人的指纹、掌纹,能够查出某些疾病。

(C)近年来,指纹又和电子计算机成了好朋友。

(D)小小的指纹将来究竟还会有哪些新的用途新的迷宫又摆在我们面前,等待着我们去探索、去寻求。

第1段文字中画横线的语句运用的说明方法是()和()。

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单项选择题
单项选择题

A child may lean against a doorpost with his or her arms folded. To the onlooker, it may look like a benign posture—however, there may be a victimized child who understands that this is the bully’s "shorthand" code of conveying the message: "Hand me your lunch as you walk by me, or else."

Bullying may be expressed in many forms. Boys are generally targeted more than girls. Boys tend to use physical aggression when they bully .by hitting, kicking, and fighting. Girls, on the other hand, more often use exclusionary techniques to bully—a form of aggression often referred to as relational aggression. Girls often start rumors, form cliques to keep certain people out, and ignore other children in attempts to show dominance over another child.

Many children who are victimized fit into one of two types: the passive victim, and the provocative victim. While people often feel bad about passive victims, provocative victims often elicit less compassion from others. Sometimes it appears that the provocative victim has "brought on" his or her own fate—but does any child deserve to be the target of repeated physical or verbal aggression Why might so-called provocative victims actively participate in being the target of bullying: For example, are their provocative gestures simply a clumsy way of attempting to interact with others One feels compassion for the inhibited child because he is reserved; a social misfortune in our society, but an aggressive child is given none of this.

The dynamics of the bully/victim relationship need to be understood in a larger context (Pepler, Craig & O’Connell, 1999). It is not only the bully and the victim that is involved in a system of interaction: The bullying context includes multiple levels of the child’s social environment. The bully may enlist the help of "henchmen" (those who assist the bully, but often do not have the initiative or leadership to initiate bullying). Also, bystanders (whether actively encouraging the bullying act or passively standing by) play a role in maintaining the pattern of bullying. Even the students who habitually flee the site of a bullying act play a role in maintaining the bully/victim interaction.

In handling the situation, it is important not to focus only on the one or two students that are directly involved, but on the playground and school as a whole. Studies have shown that in order to break down the stability of peer bullying you must initiate change on many levels: Not only in teaching the bullied child how to assert himself or herself and to deflect attacks, but also to raise awareness about the problem of bullying and encourage the school community at large to take a united stance against bullying.

The purpose of the example presented in the first paragraph is ().

A.to introduce the topic of school bullying

B.to present a clear definition for school bullying

C.to criticize those students who bully others

D.to show how prevalent school bullying is