问题 单项选择题

Many theories concerning the causes of juvenile delinquency (crimes committed by young people) focus either on the individual or on society as the major contributing influence. Theories (51) on the individual suggest that children engage in criminal behavior (52) they were not sufficiently penalized for previous misdeeds or that they have learned criminal behavior through (53) with others. Theories focusing on the role of society suggest that children commit crimes in response to their failure to rise above their socioeconomic status, (54) as a rejection of middle-class values. Most theories of juvenile delinquency have focused on children from disadvantaged families, ignoring the fact that children from wealthy homes also commit crimes. The latter may commit crimes (55) lack of adequate parental control. All theories, however, are tentative and are (56) to criticism. Changes in the social structure may indirectly (57) juvenile crime rates. For example, changes in the economy that lead to fewer job opportunities for youth and rising unemployment (58) make gainful employment increasingly difficult to obtain. The resulting discontent may in turn lead more youths into criminal behavior. Families have also (59) changes these years. More families consist of one-parent households or two working parents; consequently, children are likely to have less supervision at home (60) was common in the traditional family structure. This lack of parental supervision is thought to be an influence on juvenile crime rates.

54().

A.or 

B.but rather 

C.but 

D.or else

答案

参考答案:A

解析:

A.or:表示选择,是并列连词。B.but rather:而是,表示转折关系。C.but是“但是”,表示转折;D.or else:不然,否则。本句话的完整意思为“青少年参与犯罪活动是因为他们在以前的罪行中没有受到足够严重的惩罚,或者他们通过与其他人的交往而学会了犯罪行为。”所以应该选择并列关系的“or”。

填空题

(14分)

(1)最早使用的化学电池是锌锰电池,即大家熟悉的干电池。这种电池在使用过程中,锌外壳会逐渐变薄,最后内部糊状的电解质会泄漏出来,使电器腐蚀。后来人们采用了什么方法将其改造成了防漏电池。请列举一种方法即可_____________。

这种电池还有一个缺点:即使不用,放置过久,也会失效,请说明失效的原因_________。

(2)为提高电池寿命和提高其性能,人们将电池内的电解质NH4Cl换成湿的KOH,并在构造上做了改进,制成了碱性锌锰电池。其总反应为:

Zn + 2MnO2 + 2H2O ="===" 2MnOOH + Zn(OH)2

写出该电池正极反应式___________。电池工作时,电子流向   (填“正”或“负”)极。

(3)二氧化锰是制造锌锰干电池的基本材料。MnO2的生产方法之一是以石墨为电极,电解酸化的MnSO4溶液。阴极的电极反应式是             。若电解电路中通过2mol电子,MnO2的理论产量为               

(4)生产MnO2另一种方法:以软锰矿为原料,利用硫酸亚铁制备高纯二氧化锰。流程如下:

某软锰矿的主要成分为MnO2,还含有Si(16.72%)、Fe(5.86%)、Al(3.42%)、Zn(2.68%)和Cu(0.86%)等元素的化合物。部分阳离子以氢氧化物或硫化物的形式完全沉淀时溶液的pH见下表,回答下列问题:

沉淀物Al(OH)3Fe(OH)3Fe(OH)2Mn(OH)2Cu(OH)2Zn(OH)2CuSZnSMnSFeS
pH5.23.29.710.46.78.0≥–0.42≥2.5≥7≥7
①硫酸亚铁在酸性条件下将MnO2还原为MnSO4,酸浸时发生的主要反应的化学方程式

                              

②加入MnS的目的是除去           杂质。

单项选择题 共用题干题