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1、2021年GRE考试模拟卷（2）本卷共分为1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50题，每题2分。每题的备选项中，只有一个最符合题意） 1.Take me out to the ballgame It is a strange coincidence that many popular sports played today with a ball, big or small, were first played in the latter half of the 19th century. Only cricket set its rules ea
2、rlier, in 1788. Basketball was invented in 1891. Other sports had antecedents: soccer, rugby and American football were all formalised in the 1860s and 1870s from what appears to be a common origin, while baseball was standardised around that time, as was golf though many Scots claim earlier origins
3、. Tennis as we know it today was devised by Major Walter Clopton Wingfield, a British army officer, for the entertainment of guests at his country estate in 1873. Tennis, though, is an exception in that the indoor form of the game was played with formal rules in England and France at least as far ba
4、ck as 1600. But even this is recent compared with ulama, a game once played all over Mesoamerica, from the American Southwest to Peru. The oldest ulama court, in the Mexican state of Chiapas, was built around 1500BC, while latex balls used by the Olmecs, farther west, have been carbon-dated to 300 5
5、00 years earlier. This is not to say the rules of ulama have not changed over the years-ritual sacrifice of the losers is thought to have died out in the 1300s. But, says Manuel Aguilar, a professor at California State University, in Los Angeles, who studies the game, it is unique in having a contin
6、ual recorded history stretching back almost 4 ,000 years. Dr. Aguilar and his colleague James Brady have been directing a group of students in Sinaloa, a state in western Mexico. They have started a comprehensive study of ulama de cadera, one of three forms of ulama surviving in Sinaloa, which is pe
7、rhaps the only place where the once-widespread game is still played. Dr Aguilar speculates that this is because Sinaloa was a frontier during the time of the Spanish colonisation of the Americas, when ulama was largely eliminated by the intervention of Catholic missionaries who decried its pagan ass
8、ociations. Ulama is played on a long, narrow court, called a taste, which is 60 metres long and only four metres wide. The opposing sides, of five players each, take turns serving the four kilogram rubber ball and thereafter trying to move the ball up the field, hitting it only with the hip or upper
9、 thigh, which are protected by special garments. Points are scored if one team fails to return the others serve across the halfway point of the taste, or if the serving team succeeds in getting the ball past the opponents end line. The first team to score eight points wins. However, as Dr Aguilar an
10、d his colleagues point out in a series of papers forthcoming in the May issue of Estudios Jaliscienses, a Mexican journal, the rules of ulama are still today in flux, and often not even understood by the participants. This is why in a match each team brings a veedor, an elder who is meant to settle
11、disputes over the rules. Dr. Aguilar, though, is less concerned with the details of the rules of the game, but with its social implications, both in Sinaloa today, and in Mesoamerica generally over the course of ulamas history. While Dr Brady is, by training, an anthropologist, and so directs the te
12、ams efforts to compile an ethnography of the present-day game, Dr Aguilar is an art historian. While this may seem an unorthodox pairing, it has allowed them to make some novel insights. For example, until their recent work, it was believed in academia that ulama was only played by men. However, in
13、their detailed questioning of current players, they found that women play the game today, albeit as an exception, because female players are often stigmatized as being too macho. One of their informants is 94 years old and remembers female players from his youth, so the researchers are fairly certai
14、n that women have played throughout the 20th century. And Dr Aguilars analysis of clay figurines, he says, indicates that women played routinely in pre-Columbian times, indeed as far back as 1200BC. This leads Dr Aguilar to speculate that women stopped playing only because of Spanish intervention, a
15、nd resumed 100-200 years ago. Another concern of Dr Aguilars is the balls used to play the game. He says synthetic rubber cannot be used, as there is a strong tradition of using natural rubber. Because natural rubber is now scarce in Mexico, and the process of making a ball takes about 30 hours, the
16、 supply of balls is constraining the spread of the game. Indeed, to understand the process better, Dr Brady tried to make several balls together with his students. The process involved smearing hot latex on his hands and arms, allowing it to dry, and then peeling the strips off and wrapping them aro
17、und the core of the ball until it reaches the requisite size and weight. The traditional process, says Dr Brady, is necessary to give the ball sufficient bounce. First-hand experience has caused Dr Brady to revise his understanding of the significanATrueBFalseCNOT GIVEN 2.Why doesnt Steve want to go
18、 homeACarmgbahBSydneyCSutherlandDthe Royal National Park 3.Computing is driving the philosophical understanding of quantum theory For evidence of the power of simplicity, you need look no further than a computer. Everything it does is based on the manipulation of binary digits, or bits-units of info
19、rmation that can be either 0 or 1. Using logical operations to combine those 0s and Is allows computers to add, multiply and divide, and from there go on to achieve all the feats of the digital age. But at each step of the complex operations involved, each bit has a definite value. The same cannot b
20、e said of many properties in quantum physics, such as the spin of an atomic nucleus or the position of an electron orbiting such a nucleus. At a small scale, such properties can have more than one value at once. In 1994, Peter Shor, a mathematician then at AT&Ts Bell Laboratories in New Jersey, real
21、ised that a computer that used such quantum properties to represent information could factorise large numbers extremely quickly. This is an important problem, because much of modern cryptography is based on the difficulty of factorising large numbers - so being able to do so quickly would render man
22、y modern codes easily breakable. Then, in 1996, a colleague of Dr Shors at Bell Labs, Lov Grover, showed that such a quantum computer would be able to search through an unsorted database much faster than an ordinary computer - another important application. With these insights, quantum computing, wh
23、ich had first been thought of as a possibility in the early 1980s, became a hot topic of research. It was clear to many physicists that using qubits - which, unlike ordinary bits, can exist in a superposition of the values 0 and 1 simultaneously - might yield an exponential improvement in computing
24、power. This is because a pair of qubits could be in four different states at once, three qubits in eight, and so forth. What Dr Shor and Dr Grover showed was that the improvement, if the technological hurdles could be overcome, would be not hypothetical, but real, and useful for important problems.
25、The technology necessary to manipulate qubits, in their various incarnations, is challenging. So far, nobody has managed to get a quantum computer to perform anything other than the most basic operations. But the field has been gathering pace, and is the topic of much discussion among the scientists
26、 gathered in Montreal for the annual March meeting of the American Physical Society, the largest physics conference in the world. There are currently several different approaches to quantum computing, all of which rely on fundamentally different technologies, including ultra-cold ions that are coole
27、d by lasers, pulses of laser light, nuclear-magnetic resonance and solid-state devices such as superconducting junctions or quantum dots (which are confined clouds of electrons). What all these technologies have in common is that they can be used to invoke and exploit the bizarre phenomenon of super
28、position. Superposition is not simple. Though a qubit may, for a while, be in a state of superposition between 0 and 1, it must eventually choose between the two. And in even the best quantum computers, that choice, or decoherence, happens in a fraction of a millisecond. Just how the choice is made,
29、 and how to prolong the preceding period of coherence that allows quantum computations to be made, constitute a long-unexplained gap at the heart of modern physics. For nearly 80 years, since the inception of quantum theory in the 1920s, most physicists were content to gloss over the process. What i
30、s perhaps surprising is that the technological challenge of quantum computing is now a driving force behind efforts to understand the most abstract and philosophical underpinnings of quantum mechanics.A qubit which may be in a state of superposition between 0 and 1 can eventually choose between the
31、two.ATrueBFalseCNOT GIVEN 4.Why doesnt Steve want to go homeACarmgbahBSutherlandCSydneyDGane beach 5.Take me out to the ballgame It is a strange coincidence that many popular sports played today with a ball, big or small, were first played in the latter half of the 19th century. Only cricket set its
32、 rules earlier, in 1788. Basketball was invented in 1891. Other sports had antecedents: soccer, rugby and American football were all formalised in the 1860s and 1870s from what appears to be a common origin, while baseball was standardised around that time, as was golf though many Scots claim earlie
33、r origins. Tennis as we know it today was devised by Major Walter Clopton Wingfield, a British army officer, for the entertainment of guests at his country estate in 1873. Tennis, though, is an exception in that the indoor form of the game was played with formal rules in England and France at least
34、as far back as 1600. But even this is recent compared with ulama, a game once played all over Mesoamerica, from the American Southwest to Peru. The oldest ulama court, in the Mexican state of Chiapas, was built around 1500BC, while latex balls used by the Olmecs, farther west, have been carbon-dated
35、 to 300 500 years earlier. This is not to say the rules of ulama have not changed over the years-ritual sacrifice of the losers is thought to have died out in the 1300s. But, says Manuel Aguilar, a professor at California State University, in Los Angeles, who studies the game, it is unique in having
36、 a continual recorded history stretching back almost 4 ,000 years. Dr. Aguilar and his colleague James Brady have been directing a group of students in Sinaloa, a state in western Mexico. They have started a comprehensive study of ulama de cadera, one of three forms of ulama surviving in Sinaloa, wh
37、ich is perhaps the only place where the once-widespread game is still played. Dr Aguilar speculates that this is because Sinaloa was a frontier during the time of the Spanish colonisation of the Americas, when ulama was largely eliminated by the intervention of Catholic missionaries who decried its
38、pagan associations. Ulama is played on a long, narrow court, called a taste, which is 60 metres long and only four metres wide. The opposing sides, of five players each, take turns serving the four kilogram rubber ball and thereafter trying to move the ball up the field, hitting it only with the hip
39、 or upper thigh, which are protected by special garments. Points are scored if one team fails to return the others serve across the halfway point of the taste, or if the serving team succeeds in getting the ball past the opponents end line. The first team to score eight points wins. However, as Dr A
40、guilar and his colleagues point out in a series of papers forthcoming in the May issue of Estudios Jaliscienses, a Mexican journal, the rules of ulama are still today in flux, and often not even understood by the participants. This is why in a match each team brings a veedor, an elder who is meant t
41、o settle disputes over the rules. Dr. Aguilar, though, is less concerned with the details of the rules of the game, but with its social implications, both in Sinaloa today, and in Mesoamerica generally over the course of ulamas history. While Dr Brady is, by training, an anthropologist, and so direc
42、ts the teams efforts to compile an ethnography of the present-day game, Dr Aguilar is an art historian. While this may seem an unorthodox pairing, it has allowed them to make some novel insights. For example, until their recent work, it was believed in academia that ulama was only played by men. How
43、ever, in their detailed questioning of current players, they found that women play the game today, albeit as an exception, because female players are often stigmatized as being too macho. One of their informants is 94 years old and remembers female players from his youth, so the researchers are fair
44、ly certain that women have played throughout the 20th century. And Dr Aguilars analysis of clay figurines, he says, indicates that women played routinely in pre-Columbian times, indeed as far back as 1200BC. This leads Dr Aguilar to speculate that women stopped playing only because of Spanish interv
45、ention, and resumed 100-200 years ago. Another concern of Dr Aguilars is the balls used to play the game. He says synthetic rubber cannot be used, as there is a strong tradition of using natural rubber. Because natural rubber is now scarce in Mexico, and the process of making a ball takes about 30 h
46、ours, the supply of balls is constraining the spread of the game. Indeed, to understand the process better, Dr Brady tried to make several balls together with his students. The process involved smearing hot latex on his hands and arms, allowing it to dry, and then peeling the strips off and wrapping
47、 them around the core of the ball until it reaches the requisite size and weight. The traditional process, says Dr Brady, is necessary to give the ball sufficient bounce. First-hand experience has caused Dr Brady to revise his understanding of the significanATrueBFalseCNOT GIVEN 6.Computing is drivi
48、ng the philosophical understanding of quantum theory For evidence of the power of simplicity, you need look no further than a computer. Everything it does is based on the manipulation of binary digits, or bits-units of information that can be either 0 or 1. Using logical operations to combine those
49、0s and Is allows computers to add, multiply and divide, and from there go on to achieve all the feats of the digital age. But at each step of the complex operations involved, each bit has a definite value. The same cannot be said of many properties in quantum physics, such as the spin of an atomic nucleus or t