【正文】 aintenance 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 bee 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 11 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? Their location Their destructiveness Their formation Their disappearance 35. The word driven in the passage is closest in meaning to pushed smoothed controlled strengthened 36. The word they in the passage refers to deserts strong winds sand grains structures 37. According to the passage, in what way do sand dunes interfere with transportation? They cause travelers to get lost. They make it difficult to build and repair roadways. They increase the likelihood of accidents. They block the most direct routes. 38. The word pose in the passage is closest in meaning to solves positions presents interprets 39. One purpose of the windbreaks mentioned in the passage is to protect buildings remove sand dunes encourage the process of 12 saltation utilize the power of the wind 40. The word variability in the passage is closest in meaning to ability to cause damage tendency to change forward movement speed 41. The word substantially in the passage is closest in meaning to actually specifically frequently significantly 42. Which of the following is probably most influential in determining the shape of parabolic dunes? Moisture Vegetation Wind speed Soil position 43. It can be inferred that pinwheels resemble which of the following shapes? 44. Look at the terms saltation, migration, oases, and topography in the passage. Which of these terms is defined in the passage? Saltation Migration Oases Topography Because many predators kill only when their prey is moving, an animal that pretends to be dead may succeed in causing a predator to lose interest and move along in search of more lively prey. Hognose 13 snakes have a plex repertoire of antipredator mechanisms, of which feigning death is one option. These fairly large nonvenomous or slightly venomous snakes occur in sandy habitats in the eastern United States. When first disturbed, the hognose opts for bluffing the predator it flattens and expands the front third of its body and head, forming a hood, causing it to look larger. It then curls into an exaggerated sshaped coil and hisses, occasionally making false strikes at its tormentor. When further provoked, however, it drops the bluff and begins to twist its body violently. Then it rolls onto its back with its mouth open and tongue hanging out loosely. If the predator loses interest in the “corpse” and moves away, the snake slowly rights itself and crawls off. The plete repertoire of antipredator mechanisms occurs in young hognose snakes. Researchers have shown that newborn snakes are capable of making very subtle assessments of the degree of threat posed by a particular predator. Two experiments were conducted in which the recovery from deathfeigning (., crawling away) of newly hatched snakes under various conditions was monitored. In one experiment the recovery of snakes was monitored in the presence or absence of a stuffed screech owl mounted on a tripod one meter from the overturned snake. In another experiment the snake recovered (1) in the presence of a human staring at the snake from a distance of one meter, (2) in the presence of the same person in the same location but with eyes averted, and (3) in a control condition in which no human was visible. Both the presence of the owl and the direct human gaze resulted in longer recovery times relative to the respective control conditions. When the human eyes were averted, the recovery time was immediate. Thus, young snakes are capable of using rather subtle cues to make adjustments in their antipredator behavior. 45. From the first sentence in the passage,