题目内容

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 Bile.
C. The White Nile a branch of the Blue Nile.
D. The White Nile and the Blue Nile are branches of the River Nile.

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Why do researchers develop a new device to monitor signs of landsides？

A. Because the new device can measure the site directly.
Because the new device can be sunk into boreholes or fixed above ground.
C. Because the common methods can cause false alarms.
D. Because the common methods are useless.

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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. "
Why does the author mention "pyramid builders"？

A. Because they once worked miracles.
Because they were well-built.
C. Because they were actually very weak.
D. Because even they were unable to rescue their civilization.

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After a televised lesson, which will not happen？

A. The classroom teacher will take over for the all-important "follow-up" period.
B. The lessons will be carried into classrooms all over a city, or even an entire country.
C. The students will ask any troublesome questions.
Difficult points will be cleared up through discussion.

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In the following statements, which one will not happen in the televised lesson？

A. The teacher will still have to play an important role.
B. The chalk and erasers will still be used.
C. Each student will receive an individual lesson.
D. The lessons will be specifically geared to the students' levels of ability.

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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 Bile. C. The White Nile a branch of the Blue Nile. D. The White Nile and the Blue Nile are branches of the River Nile.

Why do researchers develop a new device to monitor signs of landsides？

After a televised lesson, which will not happen？

In the following statements, which one will not happen in the televised lesson？

A. The White Nile is the trunk of the River Nile.
B. The White Nile is the trunk of the Blue Bile.
C. The White Nile a branch of the Blue Nile.
D. The White Nile and the Blue Nile are branches of the River Nile.