Even ancient Egypt's mighty pyramid builders were powerless in the face of the famine that helped bring down their civilization around 2180 BC. Now evidence gleaned 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 southwards out of Ethiopia would have diminished these floods. Dwindling rains in the Ethiopian highlands would have meant fewer plants to stablize the soil. When rain did fall it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment from the White Nile. The Blue Nile mud has a different isotope 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 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 Egypt's Old Kingdom. The weakened waters would have been catastrophic for the Egyptians. " Changes that affect food supply don't have to be very large to have a ripple effect in societies," says Bill Ryan of the Lamont Doberty Earth Observatory in New York. "Similar events today could be even more devastating," says team member Daniel Stanley, a geoarchaeologist 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 "pyramid builders" ?
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】A：气候的变化。第一段中有这样一个子句…a shift in climate…was ultimately to blame…最终须归咎于气候的变化。在第一题的题解中，我们提到了“饥荒”与“古埃及文明毁灭”的关系。但“饥荒”是表层的因素，“气候的变化”才是古埃及文明毁灭的深层的因素。因此A是正确的答案。B：饥荒。C：水灾。D：人口增长。
单选题
Which of the following statements is true?
【正确答案】
D
【答案解析】D说的是：青尼罗河和白尼罗河是尼罗河的支流。第四段中的最后一句话是这么说的：…worked out what proportion of sediment came from each branch of the river这里的“河”是指“尼罗河”，“每条支流”是指上文所说的“青尼罗河”和“白尼罗河”。因此，D是正确的答案。A：白尼罗河是尼罗河的干流。B：白尼罗河是青尼罗河的干流。C：白尼罗河是青尼罗河的支流。显然，这些都不是答案。
单选题
According to Krom, Egypt's Old Kingdom fell______.
【正确答案】
A
【答案解析】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 predates the fall of the Egypt's Old Kingdom．其中的一个时期…就发生在古埃及王国毁灭之前。可以看出，A应该是正确的答案。B：就在一个时期的水灾之后。C：就在遇到一次旱灾之前。D：就在遇到一次水灾之前。
单选题
The word "devastating" in the last paragraph could be best replaced by______.