Even ancient Egypt's mighty pyramid (金字塔) builders were powerless in the face of the famine (饥荒)that helped bring down their civilization around 2180 B．C.. Now evidence collected from mud deposited by the River Nile suggests that a shift in climate thousands of kilometers to the south was ultimately to blame and the same or worse could happen today. The ancient Egyptians depended on the Nile's annual floods to irrigate their crops. But any change in climate that pushed the African monsoons (季风) southwards out of Ethiopia would have reduced these floods. Declining rains in the Ethiopian highlands would have meant fewer plants to stabilize 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) from the White Nile. Blue Nile mud has a different isotope (同位素) signature from that of the white Nile, so by analyzing isotope 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 Blue Nile mud in the river would be relatively high. He found that one of these periods, from 4500 to 4200 years ago, immediately came before the fall of the Egypt's old Kingdom. The weakened waters would have been disaster for the Egyptians. " Changes that affect food supply don't have to be very large to have a ripple (波浪) effect in societies. " says Bill Ryan of the Lamont Doherty Earth Observatory in New York. "Similar events today could be even more devastating," says team member Daniel Stanley, a scientist 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 today because the populations have increased dramatically. /
单选题
Why does the author mention "Egypt's mighty pyramid builders"? A．Because they once worked miracles. B．Because they were well-built. C．Because they were actually very weak. D．Because even they were unable to rescue their civilization.
单选题
Which of the following factors was ultimately responsible for bringing down the civilization of ancient Egypt? A．Change of climate. B．Corruption. C．flood. D．Population growth.
【正确答案】
A
【答案解析】[解析] 问题是：下面列出的几种因素中，哪一种是造成古埃及文明毁灭的根本性因素?第一段中有这样一个子句：…a shift in climate…was ultimately to blame-…最终归咎于气候的变化。因此，A是正确的答案。
单选题
Which of the following statements is true? A．The White Nile is the trunk of the River Nile. B．The White Nile is the trunk of the Blue Nile. C．The White Nile is a branch of the Blue Nile. D．The White Nile is a branch of the River Nile.
【正确答案】
D
【答案解析】[解析] 问题是：以下哪一种陈述正确?D说的是：白尼罗河是尼罗河的支流。第四段中的最后一句话：…worked out what proportion of sediment came from each branch of the river．算出了来自河的每条支流的沉积物的比例。因此，D是正确答案。
单选题
According to Krom, the Egypt's old Kingdom fell ______ A．immediately after a period of drought. B．immediately after a period of flood. C．just before a drought struck. D．just before a flood struck.
【正确答案】
A
【答案解析】[解析] 问题是：古埃及王朝的毁灭发生在什么时候?A说的是：就在一个时期的干旱之后。第五段有这么一个句子：…one of these periods…immediately came before the fall of the Egypt's old Kingdom．可以看出，A是正确答案。
单选题
The word "devastating" in the last paragraph could be best replaced by ______. A．"frustrating" B．"damaging" C．"defeating" D．"worrying/