托福阅读真题Official 52 Passage 3（六）

托福阅读真题Official 52 Passage 3（六）

Early Food Production in Sub-Saharan Africa

At the end of the Pleistocene(around 10,000 B.C.),the technologies of food production may have already been employed on the fringes of the rain forests of western and central Africa,where the common use of such root plants as the African yam led people to recognize the advantages of growing their own food.The yam can easily be resprouted if the top is replanted.This primitive form of“vegeculture”(cultivation of root and tree crops)may have been the economic tradition onto which the cultivation of summer rainfall cereal crops was grafted as it came into use south of the grassland areas on the Sahara’s southern borders.

As the Sahara dried up after 5000 B.C.,pastoral peoples(cattle herders)moved southward along major watercourses into the savanna belt of West Africa and the Sudan.By 3000 B.C.,just as ancient Egyptian civilization was coming into being along the Nile,they had settled in the heart of the East African highlands far to the south.The East African highlands are ideal cattle country and the home today of such famous cattle-herding peoples as the Masai.The highlands were inhabited by hunter-gatherers living around mountains near the plains until about 3300 B.C.,when the first cattle herders appeared.These cattle people may have moved between fixed settlements during the wet and dry seasons,living off hunting in the dry months and their own livestock and agriculture during the rains.

As was the case elsewhere,cattle were demanding animals in Africa.They required water at least every 24 hours and large tracts of grazing grass if herds of any size were to be maintained.The secret was the careful selection of grazing land,especially in environments where seasonal rainfall led to marked differences in graze quality throughout the year.Even modest cattle herds required plenty of land and considerable mobility.To acquire such land often required moving herds considerable distances,even from summer to winter pastures.At the same time,the cattle owners had to graze their stock in tsetse-fly-free areas.The only protection against human and animal sleeping sickness,a disease carried by the tsetse fly,was to avoid settling or farming such areas—a constraint severely limiting the movements of cattle-owning farmers in eastern and central Africa.As a result,small cattle herds spread south rapidly in areas where they could be grazed.Long before cereal agriculture took hold far south of the Sahara,some hunter-gatherer groups in the savanna woodlands of eastern and southern Africa may have acquired cattle,and perhaps other domesticated animals,by gift exchange or through raids on herding neighbors.

Contrary to popular belief,there is no such phenomenon as“pure”pastoralists,a society that subsists on its herds alone.The Saharan herders who moved southward to escape drought were almost certainly also cultivating sorghum,millet,and other tropical rainfall crops.By 1500 B.C.,cereal agriculture was widespread throughout the savanna belt south of the Sahara.Small farming communities dotted the grasslands and forest margins of eastern West Africa,all of them depending on what is called shifting agriculture.This form of agriculture involved clearing woodland,burning the felled brush over the cleared plot,mixing the ash into the soil,and then cultivating the prepared fields.After a few years,the soil was exhausted,so the farmer moved on,exploiting new woodland and leaving the abandoned fields to lie fallow.Shifting agriculture,often called slash-and-burn,was highly adaptive for savanna farmers without plows,for it allowed cereal farming with the minimal expenditure of energy.

The process of clearance and burning may have seemed haphazard to the uninformed eye,but it was not.Except in favored areas,such as regularly inundated floodplains,tropical Africa’s soils were of only moderate to low fertility.The art of farming was careful soil selection,that is,knowing which soils were light and easily cultivable,could be readily turned with small hoes,and would maintain their fertility over several years’planting,for cereal crops rapidly remove nitrogen and other nutrients from the soil.Once it had taken hold,slash-and-burn agriculture expanded its frontiers rapidly as village after village took up new lands,moving forward so rapidly that one expert has estimated it took a mere two centuries to cover 2,000 kilometers from eastern to southern Africa.

Question 11 of 14

Select the TWO answer choices that,according to paragraph 5,indicate true statements about sub-Saharan slash-and-burn agriculture.To obtain credit you must select TWO answer choices.

A.It involved a careful selection of soils for cultivation.

B.It involved regular flooding of the soils to improve fertility.

C.It was abandoned after being implemented intensively for two centuries.

D.It spread quickly once it took hold.

正确答案：AD

题目详解

题型分类：事实信息题

原文定位：整个段落都在讨论sub-Saharan slash-and-burn agriculture，可直接通过选项定位。

选项分析：

D选项：出自最后一句Once it had taken hold,slash-and-burn agriculture expanded its frontiers rapidly。

A选项出自第3句farming...careful soil selection。

B选项：soils to improve fertility出自第2句inundated floodplains...low fertility，但是regular flooding of the soils未提及，无中生有。

C选项：was abandoned无中生有。

Question 12 of 14

Which of the following best describes the relationship of paragraph 5 to paragraph 4?

A.Both paragraphs compare the effectiveness of cereal agriculture and cattle herding as food-production strategies in the sub-Saharan regions.

B.Paragraph 5 challenges the ideas in paragraph 4 about the relative importance of shifting agriculture in the sub-Saharan regions.

C.Both paragraphs emphasize the idea that agricultural practices south of the Sahara took a very long time to develop.

D.Paragraph 5 provides further details about the practice of shifting agriculture south of the Sahara presented in paragraph 4.

正确答案：D

题目详解

题型分类：修辞目的题

题干分析：问及段落间关系的题目阅读每段主旨和结构，特别注意上段结尾下段开头。

选项分析：

第4段从第4句到结尾都在讲shifting agriculture，即轮耕法，这种方法可以通过投入最少的设备和精力来耕种。第5段全段都在介绍shifting agriculture，进一步分析轮耕法的优点以及广泛传播。从4、5两段的结构来看，5段是4段的具体展开，进一步描述shifting agriculture，即选择D。

A选项与原文无关（意思是比较谷物农业和畜牧养殖业的有效性，是进一步讨论，不存在比较关系）。

B选项与原文矛盾（意思是五段质疑四段的观点，是进一步讨论，并不是反驳）。

C选项与原文无关（意思是四，五两段强调农业生产花费很长时间，是进一步讨论农耕法的发展，并没有提到发展要花很长时间）。