单选题Two techniques have recently been developed to simplify research and reduce the number of nonhuman primates needed in studies of certain complex hormonal reactions. One technique involves the culturing of primate pituitary cells and the cells of certain human turnouts. In the other, animal oviduct tissue is transplanted under the skin of laboratory primates. Both culturing techniques complement existing methods of studying intact animals. With an in vitro culturing technique, researchers are deciphering how biochemical agents regulate the secretion of prolactin, the pituitary hormone that promotes milk production. The cultured cells survive for as long as a month, and they do not require serum, a commonly used culture ingredient that can influence cellular function and confound study results. One primate pituitary gland may yield enough cells for as many as 72 culture dishes, which otherwise would require as many animals. The other technique allows scientists to monitor cellular differentiation in the reproductive tracts of female monkeys. While falling short of the long-sought goal of developing an in vitro model of the female reproductive system, the next-best alternative was achieved. The method involves transplanting oviduct tissue to an easily accessible site under the skin, where the grafted cells behave exactly as if they were in their normal environment. In about 80 percent of the grafts, blood vessels in surrounding abdominal skin grow into and begin nourishing the oviduct tissue. Otherwise, the tissue is largely isolated, walled off by the surrounding skin. A cyst forms that shrinks and swells in tandem with stages of the menstrual cycle. With about 80 percent of the grafts re-establishing themselves in the new site, a single monkey may bear as many as 20 miniature oviducts that are easily accessible for study. Because samples are removed with a simple procedure requiring only local anaesthesia, scientists can track changes in oviduct cells over short intervals. In contrast, repeated analysis of cellular changes within the oviduct itself would require abdominal surgery every time a sample was taken--a procedure that the animals could not tolerate. Scientists are using the grafting technique to study chlamydia infections, a leading cause of infertility among women. By infecting oviduct tissues transplanted into the abdominal skin of rhesus monkeys, researchers hope to determine how the bacteria cause pelvic inflammatory disease and lesions that obstruct the oviduct. Such research could eventually lead to the development of antibodies to the infectious agent and a strategy for producing a chlamydia vaccine.

单选题By almost every measure, Paul Pfingst is an unsentimental prosecutor. Last week the San Diego County district attorney said he fully intends to try suspect Charles Andrew Williams, 15, as an adult for the Santana High School shootings. Even before the tragedy, Pfingst had stood behind the controversial California law that mandates treating murder suspects as young as 14 as adults. So nobody would have wagered that Pfingst would also be the first D. A. in the U. S. to launch his very own Innocence Project. Yet last June, Pfingst told his attorneys to go back over old murder and rape convictions and see if any unravel with newly developed DNA-testing tools. In other words, he wanted to revisit past victories — this time playing for the other team. " I think people misunderstand being conservative for being biased," says Pfingst. " I consider myself a pragmatic guy, and I have no interest in putting innocent people in jail. " Around the U. S. , flabbergasted defense attorneys and their jailed clients cheered his move. Among prosecutors, however, there was an awkward pause. After all, each DNA test costs as much as $5, 000. Then there's the unspoken risk: if dozens of innocents turn up, the D. A. will have indicted his shop. But nine months later, no budgets have been busted or prosecutors ousted. Only the rare case merits review. Pfingst's team considers convictions before 1993, when the city started routine DNA testing. They discard cases if the defendant has been released. Of the 560 remaining files, they have re-examined 200, looking for cases with biological evidence and defendants who still claim innocence. They have identified three so far. The most compelling involves a man serving 12 years for molesting a girl who was playing in his apartment. But others were there at the time. Police found a small drop of saliva on the victim's shirt — too small a sample to test in 1991. Today that spot could free a man. Test results are due any day. Inspired by San Diego, 10 other counties in the U. S. are starting DNA audits.

单选题The man (was) seen run (away with) something black (under) (his arm).

单选题A. cookB. woodC. bootD. childhood

单选题Some individuals, however, have strong moral and religious beliefs A that view abortionas an act of murder and B thus to believe that the C "right to life" of an unborn child should D take precedence over .

单选题He has quite a lot of interesting magazines but I have ______.A. noB. noneC. no oneD. neither

单选题The nurses in this hospital are most ______ of the patients.

单选题Then felt like some watcher of the skies When a new planet swims into his ken, Or like stout Cortez, when with eagle eyes He stared at the Pacific--and all his men Looked at each other with a wild surmise-- Silent, upon a peak in Darien. --Keats With these well-loved lines John Keats recognized the most important geographical event in all the world, excepting only the feat of the Admiral Columbus himself. It was the discovery by European men of a vast sheet of water covering nearly 40 per cent of the globe--the ocean later to be named Pacific by Ferdinand Magellan because of its seeming tranquility. It is too bad that Keats' beautiful lines erred in naming stout Cortez instead of the equally stout Balboa, a hero of much courage and perseverance. Too bad it was, too, for the immortal Vasco Nunez de Balboa, that communications in his day were so slow and uncertain. Had they been better he might well have avoided losing his head for his pains in bringing renown to Spain and incalculable new knowledge to the civilized world. For lose it he did, under the axe at the insance of a jealous governor.

单选题It is hard to track the blue whale, the ocean"s largest creature, which has almost been killed off by commercial whaling and is now listed as an endangered species. Attaching radio devices to it is difficult, and visual sightings are too unreliable to give real insight into its behavior. So biologists were delighted early this year when, with the help of the Navy, they were able to track a particular blue whale for 43 days, monitoring its sounds. This was possible because of the Navy"s formerly top-secret system of underwater listening devices spanning the oceans. Tracking whales is but one example of an exciting new world just opening to civilian scientists after the cold war as the Navy starts to share and partly uncover its global network of underwater listening system built over the decades to track the ships of potential enemies. Earth scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption for the first time and that they plan similar studies. Other scientists have proposed to use the network for tracking ocean currents and measuring changes in ocean and global temperatures. The speed of sound in water is roughly one mile a second—slower than through land but faster than through air. What is most important, different layers of ocean water can act as channels for sounds, focusing them in the same way a stethoscope does when it carries faint noises from a patient"s chest to a doctor"s ear. This focusing is the main reason that even relatively weak sounds in the ocean, especially low-frequency ones, can often travel thousands of miles.

单选题(No wonder) that (man's) great dream has been someday to control the weather. The first step toward control is knowledge, and scientists have been (hard at work) for years trying to (keep track for) the weather.

单选题When the president entered the room, everyone ______ to welcome him.

单选题Though he would one day be considered an innovator and founding father of the artistic movement known as Impressionism, Claude Monet(1840-1926)began his career as a fairly traditional representational artist. His painting gradually changed, however, as he became interested in light and how it affects perception—an interest that led him to attempt to paint light itself rather than the objects off of which light reflected. Monet also rejected the tradition of painting in a dedicated studio, and left the confines of his dusty room to paint outside. Many of his friends and fellow artists, including Pisarro, Renoir and Cezanne, were also interested in working alfresco and joined him in painting outdoors. This group, the core of the movement that would later be classified as Impressionism, made it a common practice to paint the same scene many times in a day to explore the changes in the light, using small patches of color rather than the large brush strokes and blended color that had characterized artistic technique until that time. The Impressionists were thus attempting to evoke a mood rather than document a specific scene or event, as had been the aim of earlier painters. This move away from representation was also effected by a technological development, as photography became more affordable and popular. Before the development of photography, painting was the primary means of documenting the marriages, births, and business successes of the wealthy. Photographers soon took over much of this role because photographs were faster, more accurate, and less expensive than paintings. This freed the Impressionists to find new roles for their medium and encouraged the public to think about painting in a new way. It was no longer just a means of recording significant events; it now reflected an artist"s unique vision of a scene or moment. Today, Impressionism enjoys a privileged position with many art historians and critics, although this was certainly not always the case. As the movement was developing, most critics were at best uninterested and often appalled by the work. Even the name of the movement was originally a derisive critique. A critic who, like most of his colleagues, prized realism in paintings, declared the movement "Impressionism" after the name of the painting Impression: A Sunrise, by Monet. The critic considered the Impressionists" works unfinished—only an impression, rather than a complete painting. It is safe to say that such a critic would be in the minority today, however. Impressionist paintings are now some of the most prized works in the art world. Museums and individuals pay huge sums to add these works to their collections, and the reproductions of the artworks are among the most popular fine art posters sold.

单选题The author made a list of Sachs's positions to show that

单选题She sounded so______that everyone present believed her story.(2011年华东师范大学试题)

单选题It's a cliche—but true—that a huge obstacle to a stronger economic recovery is the lack of confidence in a strong recovery. If consumers and businesses were more confident, they would be spending, hiring and lending more freely. Instead, we're deluged with reports suggesting that, because the recession was so deep, it will take many years to regain anything like the pre-crisis prosperity. Just last week, for example, the McKinsey Global Institute released a study estimating that the country needs 21 million additional jobs by 2020 to reduce the unemployment rate to 5 percent. The study was skeptical that this would happen. Pessimism and slow growth become a vicious cycle. Battered confidence most obviously reflects the ferocity and shock of the financial collapse and the ensuing recession, including the devastating housing collapse. But there's another, less appreciated cause: disillusion with modern economics. Probably without realizing it, most Americans had accepted the fundamental promises of contemporary economics. These were: First, we know enough to prevent another Great Depression; second, although we can't prevent every recession, we know enough to ensure sustained and, for the most part, strong recoveries. These propositions, endorsed by most economists, had worked themselves into society's belief structure. Embracing them does not preclude economic disappointments, setbacks, worries or risks. But for most people most of the time, it does preclude economic calamity. People felt protected. If you stop believing them, then you act differently. You begin shielding yourself, as best you can, against circumstances and dangers that you can't foresee but that you fear are there. You become more cautious. You hesitate more before making a big commitment-buying a home or car, if you're a consumer; hiring workers, if you're an employer; starting a new business, if you're an entrepreneur; or making loans, if you're a banker. Almost everyone is hunkered down in some way. One disturbing fact from the McKinsey report is this: The number of new businesses, a traditional source of jobs, was down 23 percent in 9,010 from 2007; the level was the lowest since 1983, when America had about 75 million fewer people. Large corporations are standoffish. They have about $2 trillion of cash and securities on their balance sheets, which could be used for hiring and investing in new products. It's not that economics achieved nothing. The emergency measures thrown at the crisis in many countries exceptionally low interest rates, "stimulus" programs of extra spending and tax cuts—probably averted another Depression. But it's also true that there's now no consensus among economists as to how to strengthen the recovery. Economists suffer from what one of them calls "the pretense-of-knowledge syndrome." They act as if they understand more than they do and presume that their policies, whether of the left or right, have benefits more predictable than they actually are. It's worth remembering that the recovery's present slowdown is occurring despite measures taken to speed it up. So modern economics has been oversold, and the public is now disbelieving. The disillusion feeds stubbornly low confidence.

单选题He made ______ that he had to resign.

单选题The effect of electric technology had at first been anxiety. Now it appears to create ______. A. bore B. bored C. boredom D. bordom

单选题New ideas sometimes have to wait for years before ______.

单选题Which of the following is not a bound root morpheme?