极困惑。。。大全passage76 （13/22）

ashcroft

原文：Desertification,the creation of desert-like conditions where none had existed before, is theresult of the vagaries of weather and climate or the mismanagement of the landor, in most cases, some combination of both. Such ecological deterioration inthe Sahel hasbeen linked in several ways to the increased size of livestock herds. Duringthe fifteen years preceding 1968, a period of extremely favorable rainfall, thepastoralists moved into the marginal regions in the north with relatively largeherds. However, with the onset of a series of dry years beginning at the end ofthe rainy season in 1967, the pastoral populations found themselves overtaxingvery marginal rangelands, with the result that the nomads viewed themselves asvictims of a natural disaster. The mistaken idea that drought is an unexpectedevent has often been used to excuse the fact that long-range planning hasfailed to take rainfall variability into account. People blame the climate foragricultural failures in semiarid regions and make it a scapegoat for faultypopulation and agricultural policies.Deterioration andultimately desertification in the Sahel and in other ecosystems can be combatedonly if an ecologically realistic carrying capacity for the rangelands isdetermined. Although there appears to be widespread agreement that such adetermination would be significant, there has been little agreement on how tomake operational the concept of carrying capacity, defined as the amount ofgrazing stock that the pasture can support without deterioration of either thepasture or the stock. Should the carrying capacity (carrying capacity:承载能力) begeared to the best, the average, or the poorest years? Which combination ofstatistical measures would be most meaningful for the planning of long-termdevelopment of rangelands? On which variables should such an assessment bebased, vegetation, rainfall, soil, ground and surface water, or managerialcapabilities? Such inconclusiveness within the scientific community, whileunderstandable, creates confusion for the land managers, who often decide totake no action or who decide that all scientific suggestions are of equalweight and, therefore, indiscriminately choose any one of those suggested.Given the downward spiral of land deterioration, it becomes essential that anecologically acceptable carrying capacity be established and enforced.
Itwill also be crucial that land managers know what statistical andquasi-statistical measures actually mean: no single number can adequatelydescribe the climate regime of an arid or semiarid region. Land managers mustsupplement such terms as the “mean” with more informative statistical measuresto characterize adequately the variability of the climate. The understanding ofthis high degree of variability will serve to remove one of the major obstaclesto resolving the perennial problems of the Sahel and of other arid or semiaridregions.



3.     It can be inferred from the passage thatthe nomadic tribes who moved into the marginal regions of the Sahel did NOT
(A) enlarge thesize of their livestock herds
(B) conserve water after the drought began

(C) live in theSahel after 1968
(D) expect adrastic change in weather conditions（D）
(E)seek governmental aid in overcoming drought conditions

这题选项B和E文章哪里有提到了？我一直木有找出来～～

ashcroft

另一个类似的题目：
大全77（14/22）
2.It can be inferred from the passage that the author was unable to assess the truth of which of the following statements about opaque-2 maize?
(A) It is a more recent innovation than the use of fish-protein concentrate.
(B) It can be stored as easily as other varieties of maize.
(C) It is more popular than the wheat-rye hybrid triticale.
(D) It produces tortillas of greater protein content than do other varieties of maize.
(E) It is more susceptible to insects than are other varieties of maize.

这题目B/C两个选项我在原文中也看不出来，我也不觉得哪里可以infer出来。。。求解答。。。

原文：The promise of finding long-term technological solutions to the problem of world food shortages seems difficult to fulfill. Many innovations that were once heavily supported and publicized, such as fish-protein concentrate and protein from algae grown on petroleum substrates, have since fallen by the wayside. The proposals themselves were technically feasible, but they proved to be economically unviable and to yield food products culturally unacceptable to their consumers. Recent innovations such as opaque-2 maize, Antarctic krill, and the wheat-rye hybrid triticale seem more promising, but it is too early to predict their ultimate fate.
One characteristic common to unsuccessful food innovations has been that, even with extensive government support, they often have not been technologically adapted or culturally acceptable to the people for whom they had been developed. A successful new technology, therefore, must fit the entire sociocultural system in which it is to find a place. Security of crop yield, practicality of storage, palatability, and costs are much more significant than had previously been realized by the advocates of new technologies. For example, the better protein quality in tortillas made from opaque-2 maize will be of only limited benefit to a family on the margin of subsistence if the new maize is not culturally acceptable or is more vulnerable to insects.
The adoption of new food technologies depends on more than these technical and cultural considerations; economic factors and governmental policies also strongly influence the ultimate success of any innovation. Economists in the Anglo-American tradition have taken the lead in investigating the economics of technological innovation. Although they exaggerate in claiming that profitability is the key factor guiding technical change—they completely disregard the substantial effects of culture—they are correct in stressing the importance of profits. Most technological innovations in agriculture can be fully used only by large landowners and are only adopted if these profit-oriented business people believe that the innovation will increase their incomes. Thus, innovations that carry high rewards for big agribusiness groups will be adopted even if they harm segments of the population and reduce the availability of food in a country. Further, should a new technology promise to alter substantially the profits and losses associated with any production system, those with economic power will strive to maintain and improve their own positions. Since large segments of the populations of many developing countries are close to the subsistence margin and essentially powerless, they tend to be the losers in this system unless they are aided by a government policy that takes into account the needs of all sectors of the economy. Therefore, although technical advances in food production and processing will perhaps be needed to ensure food availability, meeting food needs will depend much more on equalizing economic power among the various segments of the populations within the developing countries themselves.

ashcroft

哎。。。木有人解答哇。。。继续。。。
大全79，
1.    The passage is primarily concerned
(A) demonstrating why the methods of early seismologists were flawed
(B) arguing that deep events are poorly understood and deserve further study
(C) defending a revolutionary theory about the causes of earthquakes and methods of predicting them
(D) discussing evidence for the existence of deep events and the conditions that allow them to occur
(E) comparing the effects of shallow events with those of deep events

答案为啥是c。。。文章第一段：
In most earthquakes the Earth’s crust cracks like porcelain. Stress builds up until a fracture forms at a depth of a few kilometers and the crust slips to relieve the stress. Some earthquakes, however, take place hundreds of kilometers down in the Earth’s mantle, where high pressure makes rock so ductile that it flows instead of cracking, even under stress severe enough to deform it like putty. How can there be earthquakes at such depths?
最后一句：How can there be earthquakes at such depths? 我认为明显是一个问题解释型的文章，不是新旧观点的对比，后面通篇都在解释这个deep earthquake是怎么去发现，怎么去解释的，哪里有defend a thoery的意思，而且c选项中“ and methods of predicting them”，我觉得文中也没有这个method～～

希望有比较擅长Main idea的朋友指点一下～谢谢～～

yoyodido

第一段The mistaken idea that drought is an unexpected event has often been used to excuse the fact that long-range planning has failed to take rainfall variability into account，，，，，，，说明是failed to take rainfall variability into account,此句的同一改写就是d....也就是说他们没有expect a drastic  change in weather condition，没有想到雨量会骤减，所以infer的是d