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TOEFL Directory > TOEFL writing > TOEFL Reading Class Unit 1_Passage 4_Question 34-44
TOEFL Reading Class Unit 1_Passage 4_Question 34-44
You have about 15 minutes to finish this passage.
First,use about 3-4 minutes to read the passage, try to understand the main idea of this passage.
Don't read it so slowly or try to remember all details.You need to do "fast reading",and "scan" the passage.
Second, read questions 1-11, and with questions you go back the passage again and look for correct answers.
Questions 34-44
Passage 4
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 on 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.
34. What aspect of sand dunes does the passage mainly discuss?
a) Their location
b) Their destructiveness
c) Their formation
d) Their disappearance
35. The word driven in the passage is closest in meaning to
a) pushed
b) smoothed
c) controlled
d) strengthened
36. The word they in the passage refers to
a) deserts
b) strong winds
c) sand grains
d) structures
37. According to the passage, in what way do sand dunes interfere with transportation?
a) They cause travelers to get lost.
b) They make it difficult to build and repair roadways.
c) They increase the likelihood of accidents.
d) They block the most direct routes.
38. The word pose in the passage is closest in meaning to
a) solves
b) positions
c) presents
d) interprets
39. One purpose of the windbreaks mentioned in the passage is to
a) protect buildings
b) remove sand dunes
c) encourage the process of saltation
d) utilize the power of the wind
40. The word variability in the passage is closest in meaning to
a) ability to cause damage
b) tendency to change
c) forward movement
d) speed
41. The word substantially in the passage is closest in meaning to
a) actually
b) specifically
c) frequently
d) significantly
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
43. It can be inferred that pinwheels resemble which of the following shapes?
a)
b)
c)
c)
44. Look at the terms salation ,migration, oases, and topography in the passage. Which of these terms is defined in the passage?
a) Saltation
b) Migration
c) Oases
d) Topography
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