Mycorrhizal fungi (mycorrhizal fungi: 菌根真菌) infect more plants than do any other fungi and are necessary for many plants to thrive, but they have escaped widespread investigation until recently for two reasons. First, the symbiotic association is so well-balanced that the roots of host plants show no damage even when densely infected. Second, the fungi cannot as yet (as yet: adv.至今) be cultivated in the absence of a living root. Despite these difficulties, there has been important new work that suggests that this symbiotic association can be harnessed to achieve more economical use of costly superphosphate fertilizer (superphosphate fertilizer: 过磷酸钙肥料) and to permit better exploitation of cheaper, less soluble rock phosphate. Mycorrhizal benefits are not limited to improved phosphate uptake in host plants. In legumes, mycorrhizal inoculation has increased nitrogen fixation beyond levels achieved by adding phosphate fertilizer (phosphate fertilizer: 磷肥(料)) alone. Certain symbiotic associations also increase the host plant’s resistance to harmful root fungi. Whether this resistance results from exclusion of harmful fungi through competition for sites, from metabolic change involving antibiotic production, or from increased vigor is undetermined.
17. Which of the following most accurately describes the passage?
(A) A description of a replicable experiment
(B) A summary report of new findings
(C) A recommendation for abandoning a difficult area of research
(D) A refutation of an earlier hypothesis
(E) A confirmation of earlier research
18. The level of information in the passage above is suited to the needs of all of the following people EXCEPT:
(A) a researcher whose job is to identify potentially profitable areas for research and product development
(B) a state official whose position requires her to alert farmers about possible innovations in farming
(C) an official of a research foundation who identifies research projects for potential funding
(D) a biologist attempting to keep up with scientific developments in an area outside of his immediate area of specialization
(E) a botanist conducting experiments to determine the relationship between degree of mycorrhizal infection and expected uptake of phosphate
19. It can be inferred from the passage that which of the following has been a factor influencing the extent to which research on mycorrhizal fungi has progressed?
(A) Lack of funding for such research
(B) Lack of immediate application of such research
(C) Lack of a method for identifying mycorrhizal fungi
(D) Difficulties surrounding laboratory production of specimens for study
(E) Difficulties ensuing from the high cost and scarcity of superphosphate fertilizers
20. The passage suggests which of the following about the increased resistance to harmful root fungi that some plants infected with mycorrhizal fungi seem to exhibit?
(A) There are at least three hypotheses that might account for the increase.
(B) An explanation lies in the fact that mycorrhizal fungi increase more rapidly in number than harmful root fungi do.
(C) The plants that show increased resistance also exhibit improved nitrogen fixation.
(D) Such increases may be independent of mycorrhizal infection.
(E) It is unlikely that a satisfactory explanation can be found to account for the increase.
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. One difficulty, however, was that few of the remaining 97 percent recorded their thoughts or had them chronicled by contemporaries. Faced with this situation, many historians based their investigations on the only records that seemed to exist: birth, marriage, and death records. As a result, much of the early work on the nonelite was aridly statistical in nature; reducing the vast majority of the population to a set of numbers was hardly more enlightening than ignoring them altogether. Historians still did not know what these people thought or felt.
One way out of this dilemma was to turn to the records of legal courts, for here the voices of the nonelite can most often be heard, as witnesses, plaintiffs, and defendants. These documents have acted as “a point of entry into the mental world of the poor.” 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. It has been societies that have had a developed police system and practiced Roman law (Roman law: n.罗马法the legal system of the ancient Romans that includes written and unwritten law, is based on the traditional law and the legislation of the city of Rome, and in form comprises legislation of the assemblies, resolves of the senate, enactments of the emperors, edicts of the praetors, writings of the jurisconsults, and the codes of the later emperors), with its written depositions, whose court records have yielded the most data to historians. In Anglo-Saxon countries hardly any of these benefits obtain, but it has still been possible to glean information from the study of legal documents.
The extraction of case histories is not, however, the only use to which court records may be put. Historians who study preindustrial Europe have used the records to establish a series of categories of crime and to quantify indictments that were issued over a given number of years. This use of the records does yield some information about the nonelite, but this information gives us little insight into the mental lives of the nonelite. We also know that the number of indictments in preindustrial Europe bears little relation to the number of actual criminal acts, and we strongly suspect that the relationship has varied widely over time. In addition, aggregate population estimates are very shaky, which makes it difficult for historians to compare rates of crime per thousand in one decade of the preindustrial period with rates in another decade. Given these inadequacies, it is clear why the case history use of court records is to be preferred.
21. The author suggests that, before the early 1950’s, most historians who studied preindustrial Europe did which of the following?
(A) Failed to make distinctions among members of the preindustrial European political and social elite.
(B) Used investigatory methods that were almost exclusively statistical in nature.
(C) Inaccurately estimated the influence of the preindustrial European political and social elite.
(D) Confined their work to a narrow range of the preindustrial European population.
(E) Tended to rely heavily on birth, marriage, and death records.
22. According to the passage, the case histories extracted by historians have
(A) scarcely illuminated the attitudes of the political and social elite
(B) indicated the manner in which those in power apportioned justice
(C) focused almost entirely on the thoughts and feelings of different social groups toward crime and the law
(D) been considered the first kind of historical writing that utilized the records of legal courts
(E) been based for the most part on the trial testimony of police and other legal authorities
23. It can be inferred from the passage that much of the early work by historians on the European nonelite of the preindustrial period might have been more illuminating if these historians had
(A) used different methods of statistical analysis to investigate the nonelite
(B) been more successful in identifying the attitudes of civil authorities, especially those who administered justice, toward the nonelite
(C) been able to draw on more accounts, written by contemporaries of the nonelite, that described what this nonelite thought
(D) relied more heavily on the personal records left by members of the European political and social elite who lived during the period in question
(E) been more willing to base their research on the birth, marriage, and death records of the nonelite
24. The author mentions Le Roy Ladurie (line 26) in order to
(A) give an example of a historian who has made one kind of use of court records
(B) cite a historian who has based case histories on the birth, marriage, and death records of the nonelite
(C) identify the author of the quotation cited in the previous sentence
(D) gain authoritative support for the view that the case history approach is the most fruitful approach to court records
(E) point out the first historian to realize the value of court records in illuminating the beliefs and values of the nonelite
25. According to the passage, which of the following is true of indictments for crime in Europe in the preindustrial period?
(A) They have, in terms of their numbers, remained relatively constant over time.
(B) They give the historian important information about the mental lives of those indicted.
(C) They are not a particularly accurate indication of the extent of actual criminal activity.
(D) Their importance to historians of the nonelite has been generally overestimated.
(E) Their problematic relationship to actual crime has not been acknowledged by most historians.
26. 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?
(A) The causes of unrest in the city during the two decades
(B) The aggregate number of indictments in the city nearest to the city under investigation during the two decades
(C) The number of people who lived in the city during each of the decades under investigation
(D) The mental attitudes of criminals in the city, including their feelings about authority, during each of the decades under investigation
(E) The possibilities for a member of the city’s nonelite to become a member of the political and social elite during the two decades
27. The passage would be most likely to appear as part of
(A) a book review summarizing the achievements of historians of the European aristocracy
(B) an essay describing trends in the practice of writing history
(C) a textbook on the application of statistical methods in the social sciences
(D) a report to the historical profession on the work of early-twentieth-century historians
(E) an article urging the adoption of historical methods by the legal profession