题目内容
【C13】
查看答案
搜索结果不匹配？点我反馈
更多问题
建筑施工企业项目经理是受企业（）委托，对工程项目施工过程全面负责的项目管理者。 A．董事会 B．股东代表大会 C．总经理 D．法定代表人
Are the engineers at Beepcard satisfied with the model they have built？ Why or why not？
Egypt Felled by Famine
Even ancient Egypt's mighty pyramid builders were powerless in the face of the famine that helped bring down their civilisation around 2180 BC. Now evidence gleaned from mud deposited by the River Nile suggests that a shift in climate thousands of kilometres 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 stablise the soil. When rain did fall it would have washed large mounts 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 analysing 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 fiver.
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 4,50Oto 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 Doherty Earth Observatory in New York.
"Similar events today could be even more devastating," says team member Daniel Stanley, a geoarchaeologist from the Smithsonian Institutions 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."
Why does the author mention "pyramid builders"？
（）是人民的根本利益所在。
微信支付 
支付宝支付