33. 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。
34. 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%.
35. 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。
36. 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。
37. 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.
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，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。
38. Even the requirement that biomaterials processed from these materials be nontoxic to host tissue can be met by techniques derived from studying the reactions of tissue cultures to biomaterials or from short-term implants.
即使是这样的要求，即从这些材料中加工出来的生物材料应该对受移植者的组织无害，也能够通过从研究组织培养对生物材料的反应而来的，或从研究短期移植而来的技术来满足。
39. But achieving necessary matches in physical properties across interfaces between living and　　nonliving matter requires knowledge of which molecules control the bonding of cells to each other—an area that we have not yet explored thoroughly.
但是，要想沿着原生和非原生物质之间的界面获取生理特性的必要匹配，需要某种知识，即什幺样的分子控制着细胞彼此间的结合——而对这一领域，我们尚未进行充分的探索。
40. Islamic law is a phenomenon so different from all other forms of law—notwithstanding, of course, a　considerable and inevitable number of coincidences with one or the other of them as far as subject matter and positive enactments are concerned—that its study is indispensable in order to　appreciate adequately the full range of　possible legal phenomena.
伊斯兰法是一种如此不同于所有其它法律形式的现象——毋庸置疑，尽管就其主要内容和有积极意义的法规而言，与其它法律形式中的这种或那种形式存在着相当数量的且不可避免的巧合相似之处——以致于对它进行研究便显得不可或缺，以便充分理解有可能存在的法律现象的全部范围。
41. （Both Jewish law and canon law are more uniform than Islamic law.） Though historically there is a discernible break between Jewish law of the sovereign state of ancient Israel and of the Diaspora （the dispersion of Jewish people after the conquest of Israel）， the spirit of the legal matter in later parts of the Old Testament is very close to that of the Talmud， one of the primary codifications of Jewish law in the Diaspora.
尽管从历史角度来看，在古代以色列作为独立主权国家的犹太教法与大流散时期（Diaspora，即以色列被征服后古代犹太人被巴比伦人逐出故土）的犹太教法之间存在着一个明晰可辨的断裂，然则，《旧约全书》（Old Testament）后半部分中法律内容的精神与《犹太教法典》（Talmud）极为一脉相承，而所谓的《犹太教法典》，是指大流散时期犹太教法的主要典籍辑录之一。
42. Islam, on the other hand, represented a radical breakaway from the Arab paganism that preceded it; Islamic law is the result of an examination,　from a religious angle, (examination) of legal subject matter that was far from uniform, comprising as it did the various components of the laws of pre-Islamic　Arabia and numerous legal elements　taken over from the non-Arab peoples　of the conquered territories. (as it did )实际上是一句插入语。
另一方面，伊斯兰教则代表着与此前存在的阿拉伯异教（Arab paganism）的一种根本上的决裂；伊斯兰法是从宗教的角度，对各种杂乱无章、绝无共同点的法律内容进行考察所致的结果，而这些法律内容实际上是由前伊斯兰阿拉伯国家（Pre-Islamic Arabia）法律的不尽相同的组成部分以及由从被征服的土地上非阿拉伯民族借鉴过来的无数法律因素所构成。
43. One such novel idea is　that (idea) of inserting into the chromosomes of plants discrete genes that are not a part of the plants’ natural constitution; specifically, the idea of inserting into nonleguminous plants the genes, if they can be identified and isolated, that fit the leguminous plants to be hosts for nitrogen-fixing bacteria. Hence, (there is ) the intensified research on legumes.
这其中的一个新颖思想就是，在植物的染色体（chromosome）内注入并非是该植物自然构造一个部分的那些不相关联的因基：具体而言，这一思想是，在非豆科植物内注入这样一些基因，倘若这些基因可被辨识出来并被分离开来，而这些基因业已使豆科植物宜于充当那些具备固氮作用的细菌的寄主。由此，对豆科植物的研究日趋深入。
44. It is　one of nature’s great ironies that the　availability of nitrogen in the soil frequently sets an upper limit on plant growth even though the plants’ leaves　are bathed in a sea of nitrogen gas.下述情形真可谓是自然界的一个莫大讽刺：土壤中所能获得的氮肥量往往对植物的生长构成了一个上限，虽然植物的叶子被沐浴在一片氮气的海洋中。
45. Unless they succeed，the　yield gains of the Green Revolution will be largely lost even if the genes in　legumes that equip those plants to enter　into a symbiosis with nitrogen fixers　are identified and isolated，and even if　the transfer of those gene complexes，once they are found， becomes possible.
除非他们能取得成功，不然的话，绿色革命的产量收益将在很大程度上损失殆尽，即使豆科植物中使这些植物有条件进入到与固氮细菌共生关系的基因可被辨识出来和分离开来的话，且即使这些基因综合体（gene complex），一旦被发现之后，其移植得以成为可能的话。
46. Its subject（to use Maynard Mack’s categories）is　"life-as-spectacle，" for readers，　　diverted by its various incidents，observe its hero Odysseus primarily from without；the tragic Iliad，however，presents "life-as-experience"：readers　are asked to identify with the mind of　　Achilles，whose motivations render him a not particularly likable hero. （5）
其主题〔若借鉴梅纳德。迈克（Maynard Mack）的两个分类范畴的话〕是“人生作为外部景象”，因为读者的注意力被作品那形形色色的事件所分散，主要是从外部来观察其主人公奥德修斯（Odyssus）的；然而，富于悲剧色彩的《伊利亚特》所表现的则是“人生作为内心体验”：读者被要求与阿基琉斯（Achilles）的心灵产生共鸣，而其行为动机却致使他变作一个并非特别惹人喜爱的主人公。 （从分号后的语句推理出前面的意思）
注：hero:主人公；without:外部；likable:有吸引力的
47. The best evidence for the layered-mantle thesis is the well-established fact that volcanic rocks found on oceanic islands, islands believed to result from mantle plumes arising from the lower mantle, are composed of material fundamentally different from that of the mid-ocean ridge system， whose source, most　geologists contend, is the upper mantle.
对于地幔分层论点来说，最好的证据乃这样一个确认的事实，即在那些海洋岛屿——这些岛屿据信是源于由下层地幔升上来的地幔柱状溶岩流（mantle plume）——上发现的火山岩石，是由与海洋中部山脊系统的物质根本不同的物质构成的，而这一海洋中部山脊系统的成因，大多数地质学家论辩道，为上部地幔。
48. Some geologists, however, on the basis of observations concerning mantle　xenoliths， argue that the mantle is　not layered, but that heterogeneity is created by fluids rich in "incompatible elements" （elements tending toward　liquid rather than solid state） percolating upward and transforming　portions of the upper mantle　irregularly, according to the vagaries of the fluids’ pathways.
但是，某些地质学家，以对地幔捕虏岩体（xenolith）所作的观察为依据，指出地幔并非是分层排列的，相反，地幔的异质性是由那些富含“不兼容成分”的流质构成的，这些成分趋向于流体而非固体的状态，自下而上渗透扩散，并依照这些流质流向的任意性，不规则地将上部地幔的某些部分予以改变。