单选题 {{B}}第三篇{{/B}}
Egypt Felled by Famine

Even ancient Egypts mighty pyramid builders were powerless in the face of the famine that helped bring down their civilian around 2180 BC. Now evidence gleaned(搜集) from mud deposited by the River Nile suggests that a shift in climate thousands of kilometers to the south was ultimately to blem -- and the same or worse could happen today.
The ancient Egyptians depended on the Niles annual floods to irrigate their crops. But any change in climate that pushed the African monsoons(季风)southwards out of Ethiopia would have diminished these floods.
Dwindling(逐渐变少;使变少)rains in the Ethiopian highlands would have meant fewer plants to establish the soil. When rain did fall it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment(沉积;沉积物)from the White Nile.
The Blue Nile mud has a different isotope signature(签名;特征) from that of the White Nile. So by analyzing isotope(同位素;核素)differences in mud deposited in the Nile Delta, Michael Krom of Leeds University worked out what proportion of sediment came from each branch of the river.
Krom reasons that during periods of drought, the amount of the Blue Nile mud in the river would be relatively high. He found that one of these periods, from 4,500 to 4,200 years ago, immediately predates the fall of the Egypts Old Kingdom.
The weakened waters would have been catastrophic for the Egyptians. Changes that affect food supply dont have to be very large to have a ripple effect in societies, says Bill Ryan of the Lamont Doherty Earth Observatory(天文台)in New York.
"Similar events today could be even more devastating, " says team member Daniel Stanley, a geoarchaeologist(地质考古学家) from the Smithsonian Institution in Washington, D. C. "Anything humans do to shift the climate belts would have an even worse effect along the Nile system because the populations have increased dramatically. "
单选题 Why does the author mention "pyramid builders"?
【正确答案】 D
【答案解析】[解析] 文章第一段提到“公元前2180年的饥荒毁灭了古埃及文明,即使是古埃及伟大的金字塔建筑者面对那场的饥荒也无能为力”,故选D。
单选题 Which of the following factors was ultimately responsible for the fall of the civilization of ancient Egypt?
【正确答案】 A
【答案解析】[解析] 文章第一段提到“他们的文明在饥荒面前也无能为力。目前从尼罗河沉积的泥浆中收集的证据表明这次饥荒最终归咎于气候的变换向南方推移了数千公里”,因此气候的变化是造成文明毁灭的根本性因素,而饥荒只是表层的因素.故选A。
单选题 Which of the following statements is true?
【正确答案】 D
【答案解析】[解析] 第四段最后一句话提到了“青尼罗河的泥浆与白尼罗河的泥浆的同位素不同。通过分析尼罗河三角洲的泥浆的同位素差别,利兹大学的迈克尔·克罗姆算出了来自每个支流的沉淀物的比例”,由此可推断出青尼罗河和白尼罗河是尼罗河的支流,故选D。
单选题 According to Krom, Egypts Old Kingdom fell
【正确答案】 A
【答案解析】[解析] 第五段提到“克罗姆推理说在干旱季节,河水中青尼罗河泥浆的量相对较高。他发现了其申一个时期,即4500年到4200年前,恰恰是埃及古王国灭亡之前”,因此可以推断出古埃及王国毁灭发生在旱灾之后.故选A。
单选题 The word "devastating" in the last paragraph could be best replaced by
【正确答案】 B
【答案解析】[解析] 此处devastating为形容词,意思是“破坏性的”,其动词是devastate,意思是“使荒芜;破坏”。A项意思是“令人失望的”;B项意思是破坏的,毁坏的;C项为defeat的现在分词形式,动词defeat意思是“击败”D项意思是“令人担忧的,令人发愁的”。各项中只有B项与devastating意义相近,故选B。