1.Only when a system possesses natural or artificial boundaries that associate the water within it the hydrologic cycle may the entire system properly be termed hydrogeologic.
难度指数(4)
译文：只有当一个系统拥有自然的或人工形成的边界来把边界中的水与水文循环联系起来的时候，才有可能把整个的系统恰当的成为与水文地质学有关。
难句类型：复杂修饰、倒装
解释：only放在句首时，主句的情态动词may倒装，这是我们高中就已经学过的东西。然而句首的only与倒装的may距离如此之远，这在以前却没有见过，所以读上去让人不习惯。另外一个难点在于，前面的由when所引导的时间状语从句中，宾语boundaries后面跟了一个定语从句，that associate the water within it with the hydrologic cycle,而且从句中的associate with又被water within it所分开，读者还要分神去考虑it所指的是什么，所以读到后面倒装的may的时候，难免不知所云。
2.The historian Frederick J. Turner wrote in the 1890’s that the agrarian discontent that had been developing steadily in the United States since about 1870 had been precipitated by the closing of the internal frontier——that is，the depletion of available new land needed for further expansion of the American farming system. (4)
难度指数(4)
译文：史学家弗雷德里克.杰.特纳(Frederick J.Turner)于十九世纪九十年代著述道，美国约自18世纪70年代以来一直在持续不断发展的农民不满，由于国内边远地区(internal frontier)的封闭而更趋加剧——亦即是说，美国农业系统进一步扩展所必需的可资利用的新土地几近耗竭。
难句类型：复杂修饰
解释：典型的句子套句子。主句是F.J.T. wrote that，宾语从句中主干是the agrarian discontent had been precipitated by the closing of the internal frontier，在从句的主语the agrarian discontent后面又来了一个定语从句。
3.In the early 1950’s，historians who studied preindustrial Europe (which we may define here as Europe in the period from roughly 1300 to 1800) began， for the first time in large numbers，to investigate more of the preindustrial European population than the 2 or 3 percent who comprised the political and social elite：the kings，generals，judges，nobles，bishops，and local magnates who had hitherto usually filled history books. (4)
难度指数(4)
难句类型：复杂修饰、插入语
译文：二十世纪五十年代早期，研究前工业化时代欧洲(此处我们可将其界定为约自1300年至1800年这一时期的欧洲)的史学家，首次以众多的人数(杨鹏的书中：第一次以大量的数据)，开始调查前工业化时代欧洲人口中的大多数，，即国王、将军、法官、贵族、主教、以及地方上的达官显贵，而正是这部分人一直到那时为止普遍充斥于史学著作。
解释：句子中有两个插入语，一个是跟在preindustrial Europe之后的which we may define here as Europe in the period from roughly 1300 to 1800,这个插入语的直接作用是解释前面的preindustrial Europe的年代，而起到的客观作用则是把主句中的主语和谓语分割得很远;第二个插入语是在began，for the first time in large numbers, to investingate中间，把一个好好的began to斩为两段。
这句话另外一个难以理解的地方是more of the preindustrial European population than the 2 or 3 percent，表示的是在工业化以前的欧洲人口中超过了那2%到3%的人，亦即占97%到98%的人民群众。
4.Historians such as Le Roy Ladurie have used the documents to extract case histories， which have illuminated the attitudes of different social groups (these attitudes include，but are not confined to，attitudes toward crime and the law)and have revealed how the authorities administered justice. (3+)
难度指数(3+)
难句类型：复杂修饰、插入语
译文：象勒罗伊。拉迪里(Le Roy Ladurie)一类的史学家利用这些文献史料从中挖掘出某些个案史(case history)来，阐明了不同社会群体的态度(这些态度包括，但并非局限于，对犯罪和法律的态度)，并揭示出当局是如何执行审判的。
解释：逗号以后的内容都是修饰逗号以前的case history的。在which引导的非限定性定语从句中有一个插入语(these attitudees includee, but are not confined to, attitudees toward crime and the law)，我们可以看到这个插入语中又套了一个插入语but not confined to。
5.It can be inferred from the passage that a historian who wished to compare crime rates per thousand in a European city in one decade of the fifteenth century with crime rates in another decade of that century would probably be most aided by better information about which of the following? (5)
难度指数(5)
难句类型：复杂修饰
译文：从文章中可以推断出来，一个希望比较十五世纪以前一个十年的某个欧洲城市中的每千人的犯罪率与另外一个十年中的犯罪率的历史学家将会被以下那种信息的提高所最好的帮助?
解释：句首的it是形式主语，其具体内容是从that开始到句子结束的全部内容。That从句中，主语a historyian之后修饰它的超长的定语从句是这个句子难以读懂的原因。Compare crime rates with crime rates中间被修饰第一个crime rates的两个修饰成分perthousand in a European city in one decade of the fifteenth century分隔得很远。在with之后的第二个crime rates后面，省略了与前面重复的per thousand in a European city。