单选题Scientists have for the first time used cloning to create human embryos that live long enough in a laboratory dish to have their stem cells harvested. The feat could set the stage for physicians to produce cells and tissues, tailored to a patient's genetic identity that can treat a wide variety of human illnesses. The accomplishment also provides a road map for how to clone a person, an even more divisive undertaking. The new work, performed in South Korea, represents "a major advance in stem cell research. It could help spur a medical revolution as important as antibiotics and vaccines", says Robert Lanza of Advanced Cell Technology (ACT), a company in Worcester, Mass., that's also investigating the promising stem cell strategy called therapeutic cloning. "However, now that the methodology is publicly available", Lanza adds, "I think it is absolutely imperative that we pass laws worldwide to prevent the technology from being abused for reproductive-cloning purposes." While some fertility doctors and a religious cult have claimed success at creating a pregnancy via cloning, they've offered no convincing proof. In contrast, the South Korean research is being reported at the meeting of the American Association for the Advancement of Science in Seattle and will appear in an upcoming Science. "This is reality," says stem cell researcher John Gearhart of Johns Hopkins University. "He4'e is a bona fide, refereed journal saying that a human embryo has been cloned and a cell line derived from it." Although ACT has not yet published a report of a cloned human blastocyst, Lanza says that the South Korean success is "consistent with our own results." Therapeutic cloning appeals to Lanza and physicians because cells made this way could have the same DNA as a patient's cells do and thus avoid rejection after they're transplanted. Seeking a compromise that would permit this strategy to be pursued, many scientists have called for legislation that would ban cloning to produce a baby but allow the creation of cloned embryos to generate stem cells for research or therapies. "The debate has been very polarized," notes bio-ethicist Laurie Zoloth of Northwestern University in Evanston.

单选题A: May I play my computer game for an hour? B: ______

单选题Chicago began life in 1779 (1) a small trading post on the Chicago River. A farsighted black freedman, Jean du Sable, did a flourishing fur (2) with the Native Americans. When his trading post became a fort and then a city, it was (3) Chicago. This is the Native American word for the wild onions found in the area. In 1820 Chicago (4) ten or twelve houses and a store or two. Now it is the third largest city in the (5) , and still it continues to grow. Thousands of new buildings are (6) every year. They are built to accommodate new businesses and residences. More than seven (7) people now live in and around the city. Astride the crossroads of the nation, Chicago is the largest railroad (8) in the world. No other city in the land is a larger trucking center. The city, (9) on lake Michigan, is the largest inland port in the world. O'Hare Airport is the world's busiest commercial airport. Overall, Chicago is the leading (10) center in the United States. Its location in the heart of North America's farmland (11) Chicago the world's largest grain market. It also plays (12) each year to more than a thousand conventions. In 1860 Abraham Lincoln was nominated for President at the Republican convention (13) here. That was to establish a pattern for both the Democratic and Republican parties since that time. Half of all major (14) conventions have taken place in Chicago. But Chicago did not achieve success without problems. At one time pollution from the Chicago River (15) the city's water supply from Lake Michigan. (16) pure drinking water, the engineers reversed the course of the river (17) it flowed backwards, away from the lake! This kept the water supply (18) . Even the famous fire of 1871 could not snuff out the spirits of the vital young giant. The entire central city was (19) , but citizens built anew. And they erected the first towering structure of steel and concrete. In doing so, they invented the (20) Today, as an example, Chicago's impressive skyline includes the world's tallest building. The 1454 foot Sears Tower.

单选题Nowhere else in the world ______ more beautiful scenery than in Switzerland.

单选题Because a degree from a good university is the means to a better job, education is one of the most ______ areas in Japanese life. A. sophisticated B. competitive C. considerate D. superficial

单选题I wonder ______ this kind of metal can be used in the construction industry.A. howB. whatC. aboutD. which

单选题Mary Anning (1799-1847) was a British fossil hunter who began finding (21) as a child, and soon supported herself and her very (22) family by finding and selling fossils. Very (23) is known about her life, but her father was a cabinet maker and he also (24) local fossils. Mary (25) on the southern coast of England, in a town called Lyme Regis. Its famous (26) by the sea contain (27) fossil layers that (28) from the Triassic, Jurassic and Cretaceous periods (the (29) of the dinosaurs, other bizarre reptiles, large insects, sea creatures, (30) mammals, and (31) life forms). Mary Anning (32) and prepared the first fossilized plesiosaur (an ocean-dwelling reptile) and the first Ichthyosaurus (an ocean-dwelling reptile that (33) like a dolphin). She found many other important fossils, including Pterodactylus (a flying reptile), sharks (and other fish), and so on. (34) with her brother Joseph, Mary supplied prepared fossil specimens to (35) museums, scientists, and private collections.

单选题Identify the author of the following quotation____:"Say Joe," was his greeting to his old-time working mate next morning, "there"s a Frenchman out on Twenty-eighth Street. He"s made a pot of money, and he"s going back to France. It"s a dandy, well-appointed, small steam laundry. There"s start for you if you want to settle down. Here, take this; buy some clothes with it and be at this man"s office by ten o"clock. He looked up the laundry for me, and he"ll take you out and show you around. If you like, and think it is worth the price— twelve thousand—let me know and it is yours. Now run along. I"m busy, I"ll see you later."

单选题They couldn' t work out what had happened. The whole situation was______.

单选题For the longest time, I couldn"t get worked up about privacy: my right to it; how it"s dying; how we"re headed for an even more wired, underregulated, overintrusive, privacy-deprived planet. I should also point out that as news director for Pathfinder, Time Inc."s mega info mall, and a guy who on the Web, I know better than most people that we"re hurtling toward an even more intrusive world. We"re all being watched by computers whenever we visit Websites; by the mere act of "browsing" (it sounds so passive!) we"re going public in a way that was unimaginable a decade ago.I know this because I"m a watcher too. When people come to my Website, without ever knowing their names, I can peer over their shoulders, recording what they look at, timing how long they stay on a particular page, following them around Pathfinder"s sprawling offerings. None of this would bother me in the least, I suspect, if a few years ago, my phone,.like Marley"s ghost, hadn"t given me a glimpse of the nightmares to come. On Thanksgiving weekend in 1995, someone (presumably a critic of a book my wife and I had just written about computer hackers) forwarded my home telephone number to an out-of-state answering machine, where unsuspecting callers trying to reach me heard a male voice identify himself as me and say some extremely rude things.Then, with typical hacker aplomb, the prankster asked people to leave their messages (which to my surprise many callers, including my mother, did). This went on for several days until my wife and I figured out that something was wrong ("Hey...why hasn"t the phone rung since Wednesday?") and got our phone service restored. It seemed funny at first, and it gave us a swell story to tell on our book tour. But the interloper who seized our telephone line continued to hit us even after the tour ended. And hit us again and again for the next six months. The phone company seemed powerless. Its security folks moved us to one unlisted number after another, half a dozen times. They put special pin codes in place. They put traces on the line. But the troublemaker kept breaking through. If our hacker had been truly evil and omnipotent as only fictional movie hackers are, there would probably have been even worse ways he could have threatened my privacy. He could have sabotaged my credit rating. He could have eavesdropped on my telephone conversations or siphoned off my e-mail. He could have called in my mortgage, discontinued my health insurance or obliterated my Social Security number. Like Sandra Bullock in The Net, I could have been a digital untouchable, wandering the planet without a connection to the rest of humanity. (Although if I didn"t have to pay back school loans, it might be worth it. Just a thought.) Still, I remember feeling violated at the time and as powerless as a minnow in a flash flood. Someone was invading my private space--my family"s private space--and there was nothing I or the authorities could do. It was as close to a technological epiphany as I have ever been. And as I watched my personal digital hell unfold, it struck me that our privacy- mine and yours- has already disappeared, not in one Big Brotherly blitzkrieg but in Little Brotherly moments, bit by bit. Losing control of your telephone, of course, is the least of it. After all, most of us voluntarily give out our phone number and address when we allow ourselves to be listed in the White Pages. Most of us go a lot further than that. We register our whereabouts whenever we put a bank card in an ATM machine or drive through an E-Z Pass lane on the highway. We submit to being photographed every day--20 times a day on average if you live or work in New York City--by surveillance cameras. We make public our interests and our purchasing habits every time we shop by mail order or visit a commercial Website.

单选题Professor White wrote a ______ report yesterday. A. two-thousand-word B. two-thousand-words' C. two-thousand-words D. two-thousands-word

单选题Many economists believed that ______ consumers would cut spending once the value of their homes began to fall. A. overstretched B. oversaturated C. overproduced D. overpopulated

单选题The current political ______ of our country is favorable for foreign investments. A. climate B. weather C. state D. occasion

单选题 The world's population continues to grow. There now are about 4 billion of us on earth. That could reach 6 billion by the end of the century and 11 billion in another 75 years. Experts long have been concerned about such growth Where will we find the food, water, jobs, houses, schools and health care for all these people? A major new study shows that the situation may be changing. A large and rapid drop in the world's birth rate has taken place during the past 10 years. Families generally are smaller now than they were a few years ago. It is happening in both developing and industrial nations, Researchers said they found a number of reasons for this. More men and women are waiting longer to get married and are using birth control devices and methods to prevent or delay pregnancy. More women are going to school or working at jobs away from their homes instead of having children. And more governments, especially in developing nations, now support family planning programs to reduce population growth. China is one of the nations that has made great progress in reducing its population growth. China has already cut its rate of population growth by about one half since 1970. China now urges each family to have no more than one child. And it hopes to reach zero population growth, the number of births equaling the number of deaths, by the year 2000. Several nations in Europe already have fewer births than deaths. Experts said that these nations could face a serious shortage of workers in the future. And the persons who are working could face much higher taxes to help support the growing number of retired people.

单选题 The climate of Earth is changing. Climatologists are confident that over the past century, the global average surface temperature has increased by about half a degree Celsius. This warming is thought to be at least partly the result of human activities, such as the burning of fossil fuels and the clearing of forests for agriculture. As the global population grows and national economies expand, the global average temperature is expected to continue increasing by an additional 1.0~C to 3.5℃by the year 2100. Climate change is one of the most important environmental issues facing humankind. Understanding the potential impacts of climate change for natural ecosystems is essential if we are going to manage our environment to minimize the negative consequences of climate change and maximize the opportunities that it may offer. Because natural ecosystems are complex, nonlinear systems, it follows that their responses to climate change are likely to be complex. Climate change may affect natural ecosystems in a variety of ways. In the short term, climate change can alter the mix of plant species in land ecosystems such as grasslands. In the long term, climate change has the potential to dramatically alter the geographic distribution of major vegetation types—savannas, forests, and climate change can also potentially alter global ecosystem processes, including the cycling of carbon, nitrogen, phosphorus, and sulfur. Moreover, changes in these ecosystem processes can affect and be affected by changes in the plant species of the ecosystem and vegetation type. All of the climate change—induced alterations of natural ecosystems affect the services that these ecosystems provide to humans. The global average surface temperature increase of half a degree .Celsius observed over the past century has been in part due to differential changes in daily maximum and minimum temperatures, resulting in a narrowing of the diurnal temperature range. Decreases in the diurnal temperature range were first identified in the United States, where large-area trends showed that maximum temperatures have remained constant or increased only slightly, whereas minimum temperatures have increased at a faster rate. In this issue, Alward etal. report on the different sensitivities of rangeland plants to minimum temperatures increases.

单选题The possibility that a virus causes human cancer is indicated by ______. A. the fact that viruses have been known to mutate B. the fact that a cancer-immune individual may lose his immunity C. the fact that production of human cancer cells might be due to a genetic factor D. the fact that man is host to many viruses

单选题Before high school teacher Kimberly Rugh got down to business at the start of a recent school week, she joked with her students about how she'd had to clean cake out of the corners of her house after her 2-year-old son's birthday party. This friendly combination of chitchat took place not in front of a blackboard but in an, E-mail message that Rugh sent to the 145 students she's teaching at the Florida Virtual School, one of the nation's leading online high schools. The school's motto is "any time, any place, any path, any pace." Florida's E-school attracts many students who need flexible scheduling, from young tennis stars and young musicians to brothers Tobias and Tyler Heeb, who take turns working on the computer while helping out. with their family's clam-farming business on Pine Island, off Florida's southwest coast. Home-schoolers also are well represented. Most students live in Florida, but 55 hail from West Virginia, where a severe teacher shortage makes it hard for many students to take advanced classes. Seven kids from Texas and four from Shanghai round out the student body. The great majority of Florida Virtual Schoolers—80 percent—are enrolled in regular Florida public or private high schools. Some are busy overachievers. Others are retaking classes they barely passed the first time. The school's biggest challenge is making sure that students aren't left to sink or swim on their own. After the school experienced a disappointing course completion rate of just 50 percent in its early years,Executive Director Julie Young made a priority out of what she calls "relationship-building," asking teachers to stay in frequent E-mail and phone contact with their students. That personal touch has helped. The completion rate is now 80 percent. Critics of online classes say that while they may have a limited place, they are a poor substitute for the face-to-face contact and socialization that take place in brick-and-mortar classrooms. Despite opportunities for online chats, some virtual students say they'd prefer to have more interaction with their peers. Students and parents are quick to acknowledge that virtual schooling isn't for everyone. "If your child's not focused and motivated, I can only imagine it would be a nightmare," says Patricia Haygood of Orlando, whose two daughters are thriving at the Florida school. For those who have what it takes, however, virtual learning fills an important niche. "I can work at my own pace, on my own time," says Hackney. "It's the ultimate in student responsibility./