26. Although these molecules allow radiation at visible wavelengths， where most of the energy of sunlight is concentrated，to pass through，they absorb some of the longer-wavelength，infrared  emissions radiated from the Earth's surface，radiation that would otherwise be transmitted back into space. 虽然这些分子允许可见波长（visible wavelength）的辐射--阳光的绝大部分能量就汇集于此--不受阻挡地穿透，但它们却会吸收某些较长波长（longer-wavelength），亦即从地球表面辐射出的红外发射（infrared emission），这种辐射若不是二氧化碳的缘故就会被重新输送回太空。

27. The role those anthropologists ascribe to evolution is not of dictating the details of human behavior but one of imposing constraints-ways of feeling，thinking，and acting that "come naturally" in archetypal situations in any culture. 这些人类学家所归诸于生物进化的作用，不是规定人类行为的种种细节，而是将各种限制强加于人类--即在任何文化的典型情景中都会"自然表露"的情感、思维、以及行动方式。

28. Which of the following most probably provides an appropriate analogy from human morphology for the "details" versus "constraints" distinction made in the passage in relation to human behavior? 以下哪一个选项最有可能为文章中所谈到的与人类行为有关的"人类行为细节"相对"人类所受限制"之间的差异，从人类形态的角度上提供了一个合适的类比？

29. A low number of algal cells in the presence of a high number of grazers suggested，but did not prove， that the grazers had removed most of the algae. 在存在大量食草动物的同时却只有少量的水藻花粉囊，这暗示出--但没能证明--食草动物已吞噬了大部分水藻。

30. Perhaps the fact many of these first studies considered  only algae of a size that could be collected in a net (net phytoplankton), a practice that overlooked the smaller phytoplankton (nannoplankton) that we now know grazers are most likely to feed on , led to a de-emphasis of the role of grazers in subsequent research. 可能这样一个事实，那就是很多这样的最初的研究只是考虑了那些能够用网捞起来的大小的水藻，这样一个忽视了更小的浮游生物（而这些浮游生物我们现在知道是捕食者主要的食物）的做法，导致了在接下来的研究中对于捕食者的作用的贬低。

31. Studies by Hargrave and Geen estimated natural community grazing rates by measuring feeding rates of individual zooplankton species in the laboratory and then computing community grazing rates for field conditions using the known population density of grazers. 由哈格雷夫（Hargrave）和吉恩（Geen）所进行的研究，对自然条件下的群落捕食速率进行了估计，其手段是通过测量出实验室内单独的浮游动物种类的捕食速率，然后利用已知的食草动物种群密度，计算出实地状况下的群落捕食速率。
 
32. In the periods of peak zooplankton abundance，that is，in the late spring and in the summer，  Haney recorded maximum daily community grazing rates，for nutrient-poor lakes and bog lakes，respectively，of 6.6 percent and 114 percent of daily phytoplankton production. 在浮游动物数量激增的高峰期，亦即在春季后期以及夏季，哈尼记录了最大程度上的每日群落食草比率，对于营养物不充足的湖和沼泽湖而言，分别为每日浮游植物繁殖量的6.6%和114%.

33. The hydrologic cycle，a major topic in this science，is the complete cycle of phenomena through which water passes，beginning as atmospheric water vapor，passing into liquid and solid form as precipitation，thence along and into the ground surface，and finally again returning to the form of atmospheric water vapor by means of evaporation and transpiration. 水文循环（hydrologic cycle），作为该学科中的一个主要课题，指的是水所经过的诸现象的整个循环过程，开始时是作为大气中的水蒸气，转而作为雨、雪、露、雹一类的降水量经过液体和固体形态，由此而沿着地层表面分布或进入地层表面，最终通过蒸发和散发作用再度回复到大气水蒸气的形态。

34. 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. 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。

35. 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。

36. 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. 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，而非那些构成了政治与社会精英阶层的百分之二或三的人口，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。

37. 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. 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。

38. 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? 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？