单选题It used to take Redwood City, California police hours to locate gunfire. Now, they have a new tool that helps them find the gunfire quickly. This new tool is called the ShotSpotter. The police began using the ShotSpotter in 1995. They wanted to cut down on gunfire in their city. One ShotSpotter covers a square mile. Eight microphones are put on the roofs of buildings. These microphones pick up gunfire noise. It only takes seven seconds to report the gunfire to the police. Then a red dot on the police map shows where the action is. The ShotSpotter really works well. It locates the gunfire within 20 to 40 feet plus or minus. Redwood City police are very happy with the ShotSpotter. They think it might have helped catch the D.C. sniper. ShotSpotters cost a lot of money. One of them sells for $200,000. Despite the cost, ShotSpotters can be a big help in fighting crime.

单选题Many a student ______ something about Abraham Lincoln． A．have known B．knows C．is known D．are known

单选题In 1844, Charles Sturt, a British soldier and colonial administrator, made an expedition ______ a supposed inland sea; his party penetrated more than 1000 miles northward, almost to the center of Australia. A. in quest of B. with regard to C. in favor of D. by way of

单选题Even plants can run a fever, especially when they're under attack by insects or disease. But unlike humans, plants can have their temperature taken from 3,000 feet away — straight up. A decade ago, adapting the infrared scanning technology developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are under stress. The goal was to let farmers precisely target pesticide (杀虫剂) spraying rather than rain poison on a whole field, which invariably includes plants that don't have pest (害虫) problems. Even better, Paley's Remote Scanning Services Company could detect crop problems before they became visible to the eye. Mounted on a plane flown at 3,000 feet at night, an infrared scanner measured the heat emitted by crops. The data were transformed into a color-coded map showing where plants were running "fevers". Farmers could then spot-spray, using 40 to 70 percent less pesticide than they otherwise would. The bad news is that Paley's company closed down in 1984, after only three years. Farmers resisted the new technology and long-term backers were hard to find. But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. "This technique can be used on 75 percent of agricultural land in the United States." says George Oerther of Texas A&M. Ray Jackson, who recently retired from the Department of Agriculture, thinks remote infrared crop scanning could be adopted by the end of the decade. But only if Pale3i finds the financial backing which he failed to obtain 10 years ago.

单选题Very few scientists ______ completely new answers to the world's problems. A. come up with B. come out C. come round D. come up to

单选题The doctor (told) him that he (should take) this medicine (one) pill at (one) time.A. toldB. shouldC. oneD. one

单选题It’s no use ______over spilt milk.

单选题This ambitious project, ______ scores of organizations around the world, will take at least ten years to be accomplished.

单选题He has never seen the Greens and he knows ______ about them.

单选题Jane always enjoys ______ to popular music at home on Friday evenings. A) listening B) being listening C) to be listening D) to listen

单选题On his way to the airport, it ( ) to him that he had forgotten to take his passport.

单选题One minute Rosemary was by my side, the next she had vanished into the crowd.

单选题After thirty years of television, people have become "speed watchers". Consequently, if the camera lingers, the interest of the audience ______.

单选题Mary: Tom, would you like to go to a party this Sunday?Tom. ______ . What kind of party? Mary: It' s a birthday party.

单选题 It is the season for some frantic last-minute math—across the country, employees of all stripes are counting backward in an attempt to figure out just how much paid time-off they have left in their reserves. More of them, though, will skip those calculations altogether and just power through the holidays into 2017: More than half of American workers don't use up all of their allotted vacation days each year. Not so long ago, people would have turned up their noses at that kind of dedication to the job. As marketing professors Silvia Bellezza, Neeru Paharia, and Anat Keinan recently explained in Harvard Business Review (HBR), leisure time was once seen as an indicator of high social status, something attainable only for those at the top. Since the middle of the 20th century, though, things have turned the opposite way—these days, punishing hours at your desk, rather than days off, are seen as the mark of someone important. In a series of several experiments, the researchers illustrated just how much we've come to admire busyness, or at least the appearance of it. Volunteers read two passages, one about a man who led a life of leisure and another about a man who was over-worked and over-scheduled; when asked to determine which of the two had a higher social status, the majority of the participants said the latter. The same held true for people who used products that implied they were short on time: In one experiment, for example, customers of the grocery-delivery service Peapod were seen as of higher status than people who shopped at grocery stores that were equally expensive; in another, people wearing wireless headphones were considered further up on the social ladder than those wearing regular headphones, even when both were just used to listen to music. In part, the authors wrote in HBR, this pattern may have to do with the way work itself has changed over the past several decades. We think that the shift from leisure-as-status to busyness-as-status may be linked to the development of knowledge-intensive economies. In such economies, individuals who possess the human capital characteristics that employers or clients value (e.g., competence and ambition) are expected to be in high demand and short supply on the job market. Thus, by telling others that we are busy and working all the time, we are implicitly suggesting that we are sought after, which enhances our perceived status. Even if you feel tempted to sacrifice your own vacation days for fake busyness, though, at least consider leaving your weekends unscheduled. It's for your own good.

单选题The reason ______ I'm writing is to tell you about my exam results.

单选题The two witnesses who saw the shootings were able to______who had fired first.