1. 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.
　　史學家弗雷德里克.杰.特納（Frederick J.Turner）于十九世紀九十年代著述道，美國約自18世紀70年代以來一直在持續(xù)不斷發(fā)展的農(nóng)民不滿，由于國內(nèi)邊遠地區(qū)（internal frontier）的封閉而更趨加劇——亦即是說，美國農(nóng)業(yè)系統(tǒng)進一步擴展所必需的可資利用的新土地幾近耗竭。
　　難句類型：復雜修飾
　　解釋：典型的句子套句子。主句是F.J.T. wrote that，賓語從句中主干是the agrarian discontent had been precipitated by the closing of the internal frontier，在從句的主語the agrarian discontent后面又來了一個定語從句。
　　意群訓練：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.
　　2. 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.
　　難句類型：復雜修飾、插入語
　　譯文：二十世紀五十年代早期，研究前工業(yè)化時代歐洲（此處我們可將其界定為約自1300年至1800年這一時期的歐洲）的史學家，首次以眾多的人數(shù)（楊鵬的書中：第一次以大量的數(shù)據(jù)），開始調(diào)查前工業(yè)化時代歐洲人口中的大多數(shù)，而非那些構成了政治與社會精英階層的百分之二或三的人口，即國王、將軍、法官、貴族、主教、以及地方上的達官顯貴，而正是這部分人一直到那時為止普遍充斥于史學著作。
　　解釋：句子中有兩個插入語，一個是跟在preindustrial Europe之后的which we may define here as Europe in the period from roughly 1300 to 1800,這個插入語的直接作用是解釋前面的preindustrial Europe的年代，而起到的客觀作用則是把主句中的主語和謂語分割得很遠；第二個插入語是在began，for the first time in large numbers, to investingate中間，把一個好好的began to斬為兩段。 這句話另外一個難以理解的地方是more of the preindustrial European population than the 2 or 3 percent，表示的是在工業(yè)化以前的歐洲人口中超過了那2%到3%的人，亦即占97%到98%的人民群眾。
　　意群訓練：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.