68. It is not known how rare this resemblance is，or whether it is most often seen ininclusions of silicates such as garnet，whose crystallography is generally somewhat similar to that of diamond； but when present，the resemblance is regarded as compelling evidence that the diamonds and inclusions are truly cogenetic. （4）
现在尚不知这种类似稀少到何种地步，也不知道是否它最常见于象石榴石一类的硅酸盐内含物中，而这类物质的晶体结构普遍地在某种程度上类似于金刚石的晶体结构。但一旦存在，这种类似就被视作极有说服力的证据，证明金刚石与内含物确是同源的。
难句类型：复杂修饰、插入语
解释：本句的句子既长，专有名词又多，从句层出不穷，故而难懂。在本句中出现的专有名词中，除了silicates硅酸盐这个单词常常出现于理科文章中，需要记忆之外，其他单词阅读现场简单处理一番既可：inclusions可以猜出是被包含的物质；garnet作首字母提炼叫g:crystallography只要能从词头推出这个单词与晶体有关即可。
意群训练：It is not known how rare this resemblance is，or whether it is most often seen ininclusions of silicates such as garnet，whose crystallography is generally somewhat similar to that of diamond；but when present，the resemblance is regarded as compelling evidence that the diamonds and inclusions are truly cogenetic.
69. Even the "radical" critiquesof this mainstream research model，such as the critique developed in Divided Society，attach the issue of ethnic assimilation too mechanically to factors of economic and socialmobility and are thus unable to illuminate the cultural subordinationof Puerto Ricans as a colonial minority. （4+）
即使是对这一主流研究模型的“激进”批评，诸如《分裂的社会》（Divided Society）一书中所提出的那种批判，亦将少数民族同化问题过分机构地与经济和社会移动性的因素联系起来，因此无从阐明波多黎各人作为一个殖民地少数民族的文化从属关系。
难句类型：复杂修饰、插入语、省略、抽象词
解释：本句实际上是由and连接的两个句子，阅读的一个难度在于，and之后省略了they(此处指前面的主语the radical critiques，)而are thus able to 又与前面离得太远，使读者难以找到主语。另外，句中的固定搭配attach A to B和illuminate C as D当中的A、B、C，全部既长又抽象，理解起来较为困难。
意群训练：Even the "radical" critiquesof this mainstream research model，such as the critique developed in Divided Society，attach the issue of ethnic assimilation too mechanically to factors of economic and socialmobility and are thus unable to illuminate the cultural subordinationof Puerto Ricans as a colonial minority.
