求教PP阅读一题

williamd

faint, i also skip it---'Parabolic dunes'

bootcat

Thanks! I miss the term "Parabolic dunes"

Thank you!

necrophile

问题其实不难，分析成分（自己的方法）。 Parabolic dunes form in areas where  vegetation anchors the side arms 是主句。 while the center is blown outward, causing sand in the middle to move forward 只是一个可以删掉的附属句罢了。翻译过来更明显： Parabolic dunes 即使在有强风致使沙子外移的情况下，也能靠vegetation固定。

注意问题上的”most influential“， 多指主句里的，换句话说是不能省略的。
hope it helps.

bootcat

About ten percent of the world’s deserts are composed of sand dunes, which are driven across the desert by the wind. Sand grains march across the desert floor under the influence of strong winds by a process known as saltation. The grains of sand become airborne for a moment, and upon landing they dislodge additional sand grains, which repeat the process. In this manner, sand dunes engulf everything in their path, including structures made by people, and pose a major problem in the construction and maintenance of highways and railroads that cross sandy areas of desert. Sand-dune migration near desert oases poses another serious problem, especially when encroaching of villages. Methods to mitigate damage to structures from sand dunes include building windbreaks and funneling sand out of the way. Without such measures, disruption of roads, airports, agricultural settlements, and towns could become a major problem in desert regions.
    The direction, strength, and variability of the wind, the moisture content of the soil, the vegetation cover, the underlying topography, and the amount of movable soil exposed to the wind determine the size and form of sand dunes. Sand dunes generally have four basic shapes, determined by the topography of the land and patterns of wind flow. Linear dunes align in roughly the direction of strong prevailing winds. Their length is substantially greater than their width, and they lie parallel to each other, sometimes with a wavy pattern. Crescent dunes, also called barchans, are symmetrically shaped, with horns pointing downwind. They travel across the desert at speeds of up to 50 feet a year. Parabolic dunes form in areas where sparse vegetation anchors the side arms while the center is blown outward, causing sand in the middle to move forward. Star dunes form by shifting winds that pile up sand into central points that can rise 1,500 feet and more, with several arms radiating outward, looking much like giant pinwheels.

42. Which of the following is probably most influential in determining the shape of parabolic dunes?

A.  Moisture
B.  Vegetation
C.  Wind speed
D.  Soil composition

bootcat

About ten percent of the world’s deserts are composed of sand dunes, which are driven across the desert by the wind. Sand grains march across the desert floor under the influence of strong winds by a process known as saltation. The grains of sand become airborne for a moment, and upon landing they dislodge additional sand grains, which repeat the process. In this manner, sand dunes engulf everything in their path, including structures made by people, and pose a major problem in the construction and maintenance of highways and railroads that cross sandy areas of desert. Sand-dune migration near desert oases poses another serious problem, especially when encroaching of villages. Methods to mitigate damage to structures from sand dunes include building windbreaks and funneling sand out of the way. Without such measures, disruption of roads, airports, agricultural settlements, and towns could become a major problem in desert regions.
    The direction, strength, and variability of the wind, the moisture content of the soil, the vegetation cover, the underlying topography, and the amount of movable soil exposed to the wind determine the size and form of sand dunes. Sand dunes generally have four basic shapes, determined by the topography of the land and patterns of wind flow. Linear dunes align in roughly the direction of strong prevailing winds. Their length is substantially greater than their width, and they lie parallel to each other, sometimes with a wavy pattern. Crescent dunes, also called barchans, are symmetrically shaped, with horns pointing downwind. They travel across the desert at speeds of up to 50 feet a year. Parabolic dunes form in areas where sparse vegetation anchors the side arms while the center is blown outward, causing sand in the middle to move forward. Star dunes form by shifting winds that pile up sand into central points that can rise 1,500 feet and more, with several arms radiating outward, looking much like giant pinwheels.

42. Which of the following is probably most influential in determining the shape of parabolic dunes?

A.  Moisture
B.  Vegetation
C.  Wind speed
D.  Soil composition

bbt

很像一起讨论，可是ppview的那儿一个test，这样容易找！

bootcat

I got the same question.

Why is not C

williamd

PP的TEST1的42题，为什么不是C,是B