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 (91) on the individual suggest that children engage in criminal behavior (92) they were not sufficiently penalized for previous misdeeds or that they have learned criminal behavior through (93) with others. Theories focusing on the role of society suggest that children commit crimes in (94) to their failure to rise above their socioeconomic status, (95) as a rejection of middle, class values.
Most theories of juvenile delinquency have focused on children from disadvantaged families, (96) the fact that children from wealthy homes also commit crimes. The latter may commit crimes (97) lack of adequate parental control. All theories, however, are tentative and are (98) to criticism.
Changes in the social structure may indirectly (99) juvenile crime rates. For example, changes in the economy that (100) to fewer job opportunities for youth and rising unemployment (101) make gainful employment increasingly difficult to obtain. The resulting discontent may in (102) lead more youths into criminal behavior.
Families have also (103) changes these years. More families consist of one-parent households or two working parents; (104) , children are likely to have less supervision at home (105) was common in the traditional family (106) . This lack of parental supervision is thought to be an influence on juvenile crime rates. Other (107) causes of offensive acts include frustration or failure in school, the increased (108) of drugs and alcohol, and the growing (109) of child abuse and child neglect. All these conditions tend to increase the probability of a child committing a criminal act, (110) a direct causal relationship has not yet been established.
A．than
B．that
C．which
D．as
参考答案：A
解析： 空格的前文是一个主干结构完整的句子，children are likely to have less supervision at home，空格的后文是：was common in the traditional family。显然这里包含了一个从句，由空格处的词连接。解题的关键词是less，它只能和than搭配构成比较级。句子的含义是：(现在的)孩子们在家里得到的父母的监护，要比(than)在传统的家庭里普遍的(监护)少(less)。需要注意than在这里的用法。than在带有比较级的句子中可以作关系代词，兼有连词和代词的性质，相当于than what，比如这句话就相当于children have less supervision than(what) was common in the traditional family。例句：The boy has eaten more food than is good for his health就相当于...eaten more food than(what) is good for his health。(那个孩子吃得太多，多得对身体都不好了。)
再看三个干扰项。that比较容易排除，它常在关系从句中做关系代词，代替先行词，可以是名词或代词。这个题目难在其他两个干扰项：which和as似乎可以放入空格中，作关系代词，代替前面整个句子，意为这种情况在传统家庭中很普遍。但考生要注意：首先，which和as的这种用法都用在非限定性从句中，即用逗号隔开，如：He took over the government，which was unlawful.(他接管了政府，这一行为实际是非法的。)She usually takes a nap after lunch．as is her habit.(午饭后她一般午睡，这已经成了习惯。)其次，填入which和as，句子的含义就成了：孩子们在家里得到的监护越来越少的现象在传统家庭中非常普遍。因为文章谈到造成孩子无人看管，正是由于家庭结构的变化，即传统的家庭变成单亲和双职工家庭所造成的。显然它们不符合上下文意。