2. 考研
  3. In the following article, some sentences have been removed. For Questions 1 — 5, choose the most suitable one from the list A—G

In the following article, some sentences have been removed. For Questions 1 — 5, choose the most suitable one from the list A—G

admin2014-07-25  4
问题 In the following article, some sentences have been removed. For Questions 1 — 5, choose the most suitable one from the list A—G to fit into each of the numbered blank. There are two extra choices which you do not need to use.
    Until about two million years ago Africa’s vegetation had always been controlled by the interactions of climate; geology, soil, and groundwater conditions; and the activities of animals. The addition of humans to the latter group, however, has increasingly rendered unreal the concept of a fully developed "natural" vegetation—i. e. , one approximating the ideal of a vegetational climax. 【R1】______. Early attempts at mapping and classifying Africa’s vegetation stressed this relationship: sometimes the names of plant zones were derived directly from climates. In this discussion the idea of zones is retained only in a broad descriptive sense.
    【R2】______. In addition, over time more floral regions of varying shape and size have been recognized. Many schemes have arisen successively, all of which have had to take views on two important aspects; the general scale of treatment to be adopted, and the degree to which human modification is to be comprehended or discounted.
    【R3】______. Quite the opposite assumption is now frequently advanced. An intimate combination of many species—in complex associations and related to localized soils, slopes, and drainage— has been detailed in many studies of the African tropics. In a few square miles there may be a visible succession from swamp with papyrus, the grass of which the ancient Egyptians made paper and from which the word "paper" originated, through swampy grassland and broad-leaved woodland and grass to a patch of forest on richer hillside soil, and finally to juicy fleshy plants on a nearly naked rock summit.
    【R4】______. Correspondingly, classifications have differed greatly in their principles for naming, grouping, and describing formations; some have chosen terms such as forest, woodland, thorn-bush, thicket, and shrub for much of the same broad tracts that others have grouped as wooded savanna(treeless grassy plain)and steppe(grassy plain with few trees). This is best seen in the nomenclature, naming of plants, adopted by two of the most comprehensive and authoritative maps of Africa’s vegetation that have been published; R. W. J. Keay’s Vegetation Map of Africa South of the Tropic of Cancer and its more widely based successor, The Vegetation Map of Africa , compiled by Frank White. In the Keay map the terms "savanna" and "steppe" were adopted as precise definition of formations, based on the herb layer and the coverage of woody vegetation; the White map, however, discarded these two categories as specific classifications. Yet any rapid absence of savanna as in its popular and more general sense is doubtful.
    【R5】______. However, some 100 specific types of vegetation identified on the source map have been compressed into 14 broader classifications.
[A]As more has become known of the many thousands of African plant species and their complex e-cology, naming, classification, and mapping have also become more particular, stressing what was actually present rather than predicting climatic potential.
[B]In regions of higher rainfall, such as eastern Africa, savanna vegetation is maintained by periodic fires. Consuming dry grass at the end of the rainy season, the fires burn back the forest vegetation, check the invasion of trees and shrubs, and stimulate new grass growth.
[C]Once, as with the scientific treatment of African soils, a much greater uniformity was attributed to the vegetation than would have been generally accepted in the same period for treatments of the lands of western Europe or the United States.
[D]The vegetational map of Africa and general vegetation groupings used here follow the White map and its extensive annotations.
[E]African vegetation zones are closely linked to climatic zones, with the same zones occurring both north and south of the equator in broadly similar patterns. As with climatic zones, differences in the amount and seasonal distribution of rainfall constitute the most important influence on the development of vegetatioa
[F]Nevertheless, in broad terms, climate remains the dominant control over vegetation. Zonal belts of rainfall, reflection latitude and contrasting exposure to the Atlantic and Indian oceans and their currents, give some reality to related belts of vegetation.
[G]The span of human occupation in Africa is believed to exceed that of any other continent. All the resultant activities have tended, on balance, to reduce tree cover and increase grassland)but there has been considerable dispute among scholars concerning the natural versus human-caused development of most African grasslands at the regional level.
【R1】
选项
答案F
解析 空格上文提到了影响非洲植被的多种因素，并强调“人类活动”对植被的影响。下文提到早期对非洲植被的研究重视“气候”与植物带的关系。上下文话题有所转变，空格处内容应该起到过渡话题的作用。另外，空格下文出现了this relationship，并以“气候”与植物带之间的密切关系进行例证，这表明空格处一定在讨论“气候”与植被之间的关系。[F]交待了climate对vegetation的重要影响，正是空格下文this relationship所指代的内容；nevertheless一词表明该选项与上文构成转折关系，从“强调人类活动的影响”转向“强调气候的影响”。[F]最后出现的belts of vegetation与空格下文plant zones是同义表达，相互呼应。[E]虽然出现了关键词climate和vegetation，但它主要论述的是“气候带(climatic zones)”，而非“气候”对非洲植被的影响，而且该选项与上文话题之间转换突兀，故予以排除。
转载请注明原文地址:https://www.kaotiyun.com/show/PWK4777K
0

考研英语一

相关试题推荐
随机试题
最新回复(0)