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1、2021GRE考试模拟卷（8）本卷共分为2大题50小题，作答时间为180分钟，总分100分，60分及格。一、单项选择题（共25题，每题2分。每题的备选项中，只有一个最符合题意） 1. Geographers say that what defines a place are four properties: soil, climate, altitude, and aspect, or attitude to the Sun. Floridas ancient scrub demonstrates this principle. Its soil is pure silica, so barr
2、en it supports only lichens as ground cover.(It does, however, sustain a sand-swimming lizard that cannot live where there is moisture or plant matter (5) the soil.) Its climate, despite more than 50 inches of annual rainfall, is blistering desert plant life it can sustain is only the xerophytic, th
3、e quintessentially dry. Its altitude is a mere couple of hundred feet, but it is high ground on a peninsula elsewhere close to sea level, and its drainage is so critical that a difference of inches in elevation can bring major changes in its plant communities. Its aspect is flat, direct, brutaland s
4、ubtropical. (10) Floridas surrounding lushness cannot impinge on its desert scrubbiness. This does not sound like an attractive place. It does not look much like one either; Shrubby little oaks, clumps of scraggly bushes, prickly pear, thorns, and tangles. It appear Said one early naturalist, to des
5、ire to display the result of the misery through which it has Passed and is passing. By our narrow standards, scrub is not beautiful; neither does it meet (15) our selfish utilitarian needs. Even the name is an epithet, a synonym for the stunted, the scruffy, the insignificant, what is beautiful abou
6、t such a place The most important remaining patches of scrub lie along the Lake Wales Ridge, a chain of paleoislands running for a hundred miles down the center of Florida, in most places less than ten miles wide. R is relict seashore, tossed up millions of years ago when ocean levels (20) were high
7、er and the rest of the peninsula was submerged. That ancient emergence is precisely what makes Lake Wales Ridge so precious: it has remained unsubmerged , its ecosystems essentially undisturbed, since the Miocene era. As a result, it has gathered to itself one of the largest collections of rare orga
8、nisms in the world. Only about 75 plant species survive there, but at least 30 Of these are found nowhere else on Earth.The author mentions the prickly pear (line 12) as an example ofAvaluable fruit-bearing plants of the scrub areaBunattractive plant life of the scrub areaCa pant discovered by an ea
9、rly naturalistDplant life that is extremely are 2. Because the low latitudes of the Earth, the areas near the equator, receive more heat Than the latitudes near the poles, and because the nature of heat is to expand and move, Heat is transported from the tropics to the middle and high latitudes. Som
10、e of this heat is Moved by winds and some by ocean currents, and some gets stored in the atmosphere in(5) the form of latent heat. The term latent heat refers to the energy that has to be used to Convert liquid water to water vapor. We know that if we warm a pan of water on a stove, it will evaporat
11、e, or turn into vapor, faster than if it is allowed to sit at room temperature. We also know that if we hang wet clothes outside in the summertime they will dry faster than in winter, when temperatures are colder. The energy used in both cases to change (10) liquid water to water vapor is supplied b
12、y heatsupplied by the stove in the first case and by the Sun in the latter case. This energy is not lost. It is stored in water vapor in the atmosphere as latent heat. Eventually, the water stored as vapor in the atmosphere will condense to liquid again, and the energy will be released to the atmosp
13、here. In the atmosphere, a large portion of the Suns incoming energy is used to evaporate (15) Water, primarily in the tropical oceans. Scientists have tried to quantify this proportion of the Suns energy. By analyzing temperature, water vapor, and wind data around the globe, they have estimated the
14、 quantity to be about 90 watts per square meter, or nearly 30 percent of the Suns energy. Once this latent heat is stored within the atmosphere, it can be transported, primarily to higher latitudes, by prevailing, large-scale winds. Or it (20) can be transported vertically to higher levels in the at
15、mosphere, where it forms clouds and subsequent storms, which then release the energy back to the atmosphere.According to the passage, most ocean water evaporation occurs especiallyAaround the higher latitudesBin the tropicsCbecause of large-scale windsDbecause of strong ocean currents 3.Both in what
16、 is now the eastern and the southwestern United States, the peoples of the Archaic era (8,000-1,000 B.C) were, in a way, already adapted to beginnings of cultivation through their intensive gathering and processing of wild plant foods. In both areas, there was a well-established ground stone tool te
17、chnology, a method of pounding(5) and grinding nuts and other plant foods, that could be adapted to newly cultivated foods. By the end of the Archaic era, people in eastern North America had domesticated certain native plants, including sunflowers; weeds called goosefoot, sumpweed, or marsh elder; a
18、nd squash or gourds of some kind. These provided seeds that were important sources of carbohydrates and fat in the diet.(10) The earliest cultivation seems to have taken place along the river valleys of the Midwest and the Southeast, with experimentation beginning as early as 7,000 years ago and dom
19、estication beginning 4,000 to 2,000 years ago. Although the term “Neolithic” is not used in North American prehistory, these were the first steps toward the same major subsistence changes that took place during the Neolithic (8,000-2,000 B.C.) period(15) elsewhere in the world. Archaeologists debate
20、 the reasons for beginning cultivation in the eastern part of the continent. Although population and sedentary living were increasing at the time, there is little evidence that people lacked adequate wild food resources; the newly domesticated foods supplemented a continuing mixed subsistence of hun
21、ting, fishing, and gathering(20) wild plants, Increasing predictability of food supplies may have been a motive. It has been suggested that some early cultivation was for medicinal and ceremonial plants rather than for food. One archaeologist has pointed out that the early domesticated plants were a
22、ll weedy species that do well in open, disturbed habitats, the kind that would form around human settlements where people cut down trees, trample the ground, deposit trash, and (25) dig holes. It has been suggested that sunflower, sumpweed, and other plants almost domesticated themselves, that is ,
23、they thrived in human disturbed habitats, so humans intensively collected them and began to control their distribution. Women in the Archaic communities were probably the main experimenters with cultivation, because ethnoarchaeological evidence tells us that women were the main collectors of plant f
24、ood and had detailed knowledge of plants.According to the passage, which of the following was a possible motive for the cultivation of plants in eastern North AmericaALack of enough wild food sourcesBThe need to keep trees from growing close to settlementsCProvision of work for an increasing populat
25、ionDDesire for the consistent availability of food 4. Geographers say that what defines a place are four properties: soil, climate, altitude, and aspect, or attitude to the Sun. Floridas ancient scrub demonstrates this principle. Its soil is pure silica, so barren it supports only lichens as ground
26、cover.(It does, however, sustain a sand-swimming lizard that cannot live where there is moisture or plant matter (5) the soil.) Its climate, despite more than 50 inches of annual rainfall, is blistering desert plant life it can sustain is only the xerophytic, the quintessentially dry. Its altitude i
27、s a mere couple of hundred feet, but it is high ground on a peninsula elsewhere close to sea level, and its drainage is so critical that a difference of inches in elevation can bring major changes in its plant communities. Its aspect is flat, direct, brutaland subtropical. (10) Floridas surrounding
28、lushness cannot impinge on its desert scrubbiness. This does not sound like an attractive place. It does not look much like one either; Shrubby little oaks, clumps of scraggly bushes, prickly pear, thorns, and tangles. It appear Said one early naturalist, to desire to display the result of the miser
29、y through which it has Passed and is passing. By our narrow standards, scrub is not beautiful; neither does it meet (15) our selfish utilitarian needs. Even the name is an epithet, a synonym for the stunted, the scruffy, the insignificant, what is beautiful about such a place The most important rema
30、ining patches of scrub lie along the Lake Wales Ridge, a chain of paleoislands running for a hundred miles down the center of Florida, in most places less than ten miles wide. R is relict seashore, tossed up millions of years ago when ocean levels (20) were higher and the rest of the peninsula was s
31、ubmerged. That ancient emergence is precisely what makes Lake Wales Ridge so precious: it has remained unsubmerged , its ecosystems essentially undisturbed, since the Miocene era. As a result, it has gathered to itself one of the largest collections of rare organisms in the world. Only about 75 plan
32、t species survive there, but at least 30 Of these are found nowhere else on Earth.The author suggests that human standards of beauty areAtolerantBidealisticCdefensibleDlimited 5.Perhaps one of the most dramatic and important changes that took place in the Mesozoic era occurred late in that era, amon
33、g the small organisms that populate the uppermost, sunlit portion of the oceans-the plankton. The term plankton is a broad one, designating all of the small plants and animals that float about or weakly propel(5) themselves through the sea. In the late stages of the Mesozoic era. during the Cretaceo
34、us period, there was a great expansion of plankton that precipitated skeletons or shells composed of two types of mineral: silica and calcium carbonate. This development radically changed the types of sediments that accumulated on the seafloor, because, while the organic parts of the plankton decaye
35、d after the organisms died, their mineralized(10)skeletons often survived and sank to the bottom. For the first time in the Earths long history, very large quantities of silica skeletons, which would eventually harden into rock, began to pile up in parts of the deep sea. Thick deposits of calcareous
36、 ooze made up of the tiny remains of the calcium carbonate-secreting plankton also accumulated as never before. The famous white chalk cliffs of Dover, in the southeast of England, are just one(15)example of the huge quantities of such material that amassed during the Cretaceous period; there are ma
37、ny more. Just why the calcareous plankton were so prolific during the latter part of the Cretaceous period is not fully understood. Such massive amounts of chalky sediments have never since been deposited over a comparable period of time. The high biological productivity of the Cretaceous oceans als
38、o led to ideal conditions(20)for oil accumulation. Oil is formed when organic material trapped in sediments is slowly buried and subjected to increased temperatures and pressures, transforming it into petroleum. Sediments rich in organic material accumulated along the margins of the Tethys Seaway, t
39、he tropical east-west ocean that formed when Earths single landmass (known as Pangaea) split apart during the Mesozoic era. Many of todays important oil(25)fields are found in those sediments-in Russia, the Middle East, the Gulf of Mexico, and in the states of Texas and Louisiana in the United State
40、s.According to the passage, the most dramatic change to the oceans caused by plankton during the Cretaceous period concernedAthe depth of the waterBthe makeup of the sediment on the ocean floorCthe decrease in petroleum-producing sedimentDa decline in the quantity of calcareous ooze on the seafloor
41、6. Some animal behaviorists argue that certain animals can remember past events,anticipate future ones, make plans and choices, and coordinate activities within a group. These scientists, however, are cautious about the extent to which animalscan be credited with conscious processing.(5) Explanation
42、s of animal behavior that leave out any sort of consciousness at all and ascribe actions entirely to instinct leave many questions unanswered. One example of such unexplained behavior: Honeybees communicate the sources of nectar to one another by doing a dance in a figure-eight pattern. The orientat
43、ion of the dance conveys the position of the food relative to the suns position in the sky,(10)and the speed of the dance tells how far the food source is from the hive. Most researchers assume that the ability to perform and encode the dance is innate and shows no special intelligence. But in one s
44、tudy, when experimenters kept changing the site of the food source, each time moving the food 25 percent farther from the previous site, foraging honeybees began to anticipate where the food source would(15)appear next. When the researchers arrived at the new location, they would find the bees circl
45、ing the spot, waiting for their food. No one has yet explained how bees,whose brains weigh four ten-thousandths of an ounce, could have inferred the location of the new site. Other behaviors that may indicate some cognition include tool use. Many(20)animals, like the otter who uses a stone to crack
46、mussel shells, are capable of using objects in thenatural environment as rudimentary tools. One researcher has found that mother chimpanzeesoccasionally show their young how to use tools to open hard nuts. In one study, chimpanzeescompared two pairs of food wells containing chocolate chips. One pair
47、 might contain, say, fivechips and three chips, the other(25)our chips and three chips. Allowed to choose which pair they wanted, thechimpanzees almost always chose the one with the higher total, showing some sort of summingability. Other chimpanzees have learned to use numerals to label quantities of items and do simple sums.What did researchers discover in the study of honeybees discussed in paragraph 2ABees are able to travel at greater speeds than scientists thought.BThe bees