单选题Two keys are to be put into the key chain that already has 5 keys. What is the probability that these two keys will be next to each other?

单选题Which of the following is the coefficient of xy in3x+4y-xy4x+3y+1?

单选题11. Samples taken from the ice of glaciers show that during the last ice age there was far more dust in the atmosphere than there is now. Since greater amounts of dust in the atmosphere would result in less sunlight's reaching the Earth's surface, it is likely that the large amount of dust then present helped maintain low global temperatures and thus prolonged the ice age. Which of the following, if true, most seriously weaken the argument? ______

单选题 ①The United States Civil Rights movement

单选题One hour after Tom started walking from X to Y, a distance of 45 miles. Bob started walking along the same road from Y to X. If Tom’s walking rate was 3 miles per hour and Bob’s was 4 miles per hour,

单选题. ①Throughout much of the Tertiary period(most of the past 65 million years), the Arctic supported continuous forests. ②Only toward the end of that period does the fossil evidence show that certain present-day Arctic plants were established and widely distributed throughout the Arctic. ③Many Arctic plants are thought to have originated in the high mountain ranges of central Asia and North America, to have spread northward to the Arctic as global temperatures fell in the late Tertiary, and to have achieved a circumpolar distribution by the end of the Tertiary(about 2 million years ago). ④However, fossil evidence to support these proposals is either lacking or fragmentary. ⑤Consequently, the routes by which these plants expanded their ranges during their colonization of the Arctic remain unknown.15. Which of the following statements about Arctic plants is supported by the passage? ______

单选题. ①Benjamin Franklin is portrayed in American history as the quintessential self-made man. ②In "Self-reliance," Emerson asks, "Where is the master who could have instructed Franklin...?" ③In fact, Franklin took instruction widely, and his scientific work was highly collaborative. ④Friends in England sent equipment needed for his electrical experiments, others, in Philadelphia, helped him set up his workshop there. ⑤Philip Syng constructed a device for generating electrical charges, while Tomas Hopkinson demonstrated the potential of pointed conductors. ⑥Franklin, in addition to being the group's theoretician, wrote and published its results. ⑦His fame as an individual researcher is partly a consequence of the shorthand by which when one person writes about a group's discoveries, history sometimes grants singular credit for collective effort.45. Which of the following best describes the function of the highlighted sentence? ______

单选题3. The use of nets at beach resorts to protect swimming areas from sharks has been criticized by environmentalists because the nets needlessly kill thousands of marine animals annually. However, environmentalists have recently discovered that an electrified cable buried beneath the periphery of swimming areas causes sharks to swim away while harming neither humans nor marine life. Hence, by installing such cables, resort communities will be able to maintain tourism while satisfying environmentalists' concerns. Which of the following, if true, most seriously weakens the argument? ______

单选题. ①David Belasco's 1912 Broadway production of The Governor's Lady created a sensation with a scene set in a Child's cafeteria, a chain restaurant that was an innovator in food standardization and emblematic of modern everyday life. ②While Belasco's meticulously detailed reproduction of an immediately recognizable setting impressed the public, it was derided by progressive theater critics who championed the New Stagecraft theories of European artists like Max Reinhardt. ③The New Stagecraft rejected theatrical literalism; it drew inspiration from the subjectivity and minimalism of modern painters, advocating simplified sets designed to express a dramatic text's central ideas. ④Such critics considered Belasco a craftsman who merely captured surface realities: a true artist eliminated the inessential to create more meaningful, expressive stage images.47. The author of the passage implies which of the following about Belasco's production of The Governor's Lady? ______

单选题Both m and n are positive integers greater than 1.If 23m-2=21n-3，what is the least possible value of m+n?

单选题. ①The main exception to primate researchers' general pattern of ignoring interactions between males and infants has been the study of male care among monogamous primates. ②It has been known for over 200 years, ever since a zoologist-illustrator named George Edwards decided to watch the behavior of pet marmosets in a London garden, that among certain species of New World monkeys males contributed direct care for infants that equaled or exceeded that given by females. ③Mothers among marmosets and tamarins typically give birth to twins, as often as twice a year, and to court the female in her staggering reproductive burden the male carries the infant at all times except when the mother is actually suckling it. ④It was assumed by Kleiman that monogamy and male confidence of paternity were essential to the evolution of such care, and at the same time, it was assumed by Symons and others that monogamy among primates must be fairly rare. ①Recent findings, however, make it necessary to reverse this picture. ②First of all, monogamy among primates turns out to be rather more frequent than previously believed (either obligate or facultive monogamy can be documented for some 17-20 percent of extant primates) and second, male care turns out to be far more extensive than previously thought and not necessarily confined to monogamous species, according to Hrdy. ③Whereas previously, it was assumed that monogamy and male certainty of paternity facilitated the evolution of male care, it now seems appropriate to consider the alternative possibility, whether the extraordinary capacity of male primates to look out for the fates of infants did not in some way pre-adapt members of this order for the sort of close, long-term relationships between males and females that, under some ecological circumstances, leads to monogamy! ④Either scenario could be true. ⑤The point is that on the basis of present knowledge there is no reason to view male care as a restricted or specialized phenomenon. ⑥In sum, though it remains true that mothers among virtually all primates devote more time and/or energy to rearing infants than do males, males nonetheless play a more varied and critical role in infant survival than is generally realized.37. The author the passage mentions the work of Hrdy primarily to ______

单选题21. Almost all forms of large-scale electric power generation pollute the environment; the less electric power consumed, therefore, the less pollution created. Ordinary refrigerators account for 15 percent to 25 percent of the average United States household's annual electric power consumption, but energy efficient refrigerators use 20 percent to 30 percent less electricity than ordinary refrigerators. If the information above is correct, which of the following conclusions does it best support? ______

单选题 ①In the late nineteenth century

单选题the average of n consecutive integers beginning with 1 is 12Quantity A: nQuantity B: 24

单选题2. The Rivera Art Museum recently began charging admission. The resulting decline in visitors has been far larger than at other local museums, which have also begun charging admission. The magnitude of the decline might be due to the Rivera's location near government offices. Because an admission charge is most discouraging to those who plan a short visit, it is likely that government workers who formerly made brief visits during lunchtime and after work now do not. Which of the following, if true, most seriously undermines the proposed explanation? ______

单选题 ①According to the prevailing view, Homo erectus

单选题 The surface of Venus contains calcite

单选题. ①Migratory songbirds breeding in Eurasia's temperate forests depend on a summer flush of insects, particularly caterpillars, to feed themselves and their offspring. ②In some places, these caterpillars are emerging earlier in responses to rising global temperatures. ③In theory, the songbird could simply push up their departure from their winter quarters to catch the earlier flush of insect prey. ④If, however, the birds rely on a fixed cue such as increasing day length to begin flying north, they may be unable to adjust the timing of their migration. ⑤Precisely this disruption in the emergence of insects relative to the timing of songbird migration has been identified as the cause of a significant decline in populations of pied flycatchers in the Netherlands.25. The primary function of the highlighted sentence is to ______

单选题Quantity A: 111+112+113+114+115Quantity B: 13

单选题 ①Hotter and more massive than the Sun