单选题"How long has this shoes shop been in business?"" ______1996."

单选题Sound moves from its source to the ear by wave like fluctuations in air pressure, something like the peaks and troughs or the lowest point of ocean waves. One way to keep from hearing sound is to use ear plugs. Another way is to cancel out the sound with anti-sound. Using a noise maker controlled by a microprocessor, engineers have produced sound waves that are half a wavelength out of phase with those of the noise to be quieted--each peak is matched to a trough, and vice versa. Once the researchers have recorded the offending sound, a microprocessor calculates the amplitude and wavelength of sound that will cancel out the highest and lowest points of the noise. It then produces an electric current that is amplified and fed to a loudspeaker, which produces anti-sound and wipes out the noise. If the anti-sound goes out of synchronization, a microphone picks up the leftover sound and sends it back to the microprocessor, which changes the phase of the anti-sound just enough to cause complete silence. The research team has concentrated on eliminating low-frequency noise from ship engines, which causes fatigue that can impair the efficiency and alertness of the crew, and may mask the warning sounds of alarm and fog signals.

单选题Contestants who do not{{U}} comply with {{/U}}the regulations will be disqualified.

单选题The American central bank was reluctant to raise interest rates because

单选题Many different parts Umake up/U an airplane: the engine(s), the wings, the tail, and so on.

单选题______ opposing views, our boss declared that the company would enter the furniture market.

单选题It was ______ last week ______ I knew the news.

单选题In today' s rapidly changing economy, opportunities ______for those who are motivated and dedicated to achieving their career goals.

单选题Before she could shout "look ______ "to the old man, he was run by a car coining from his left.

单选题此题为音频题

单选题______energy under the earth must be released in one form or another, for example, an earthquake.

单选题This research has attracted wide coverage in the ______ and has featured on BBC television"s Tomorrow"s World.

单选题Living in Brazil 巴西）and SwitzerlandMoving to a different city may seem difficult. You have to change schools and get used to your new home. But you can always go back to that city to visit. When you m

单选题Despite his ______ as a trouble-maker, he was promoted to department manger. A. repetition B. repression C. reputation D. representation

单选题Although Alice had expected her parents to be worried by her long, unexplained absence, both her mother and father seemed quite ______.

单选题 Results showed that at least a tenth of the Harvard first-year undergraduates polled admitted to having cheated on an exam prior to starting at the university, while almost half admitted to cheating on their homework. An anonymous survey by Harvard's newspaper has revealed a surprising pattern of academic dishonesty among students entering the US universities. The survey by The Harvard Crimson was emailed to the incoming first year undergraduates; 1,600 students responded. Results showed that at least a tenth of the students polled admitted to having cheated on an exam prior to starting at the university, while almost half admitted to cheating on their homework. Athletes were apparently the most prone to cheating. 20 percent of students who played a university sport admitted to cheating on an exam compared to 9 percent of students who did not. The survey also revealed that men were not only more likely to cheat but were also more likely to admit to it. The results, compared to a previous survey done on the class of 2013, suggested that cheating may be becoming more commonplace. Of the outgoing seniors only 7 percent admitted to cheating in an exam and another 7 percent said they had been dishonest on a take-home test. 32 percent of the seniors said they had cheated on homework during their undergraduate years... The surveys come in the wake of a cheating scandal at the university which saw 120 students investigated for sharing answers on an exam in 2012. One recent graduate stated: 'Cheating was commonplace when I was at Harvard, especially with students in their first year or two. I would say as many as 60 percent of students took notes into some exams. No one really cared the faculty, well some of them at least, seemed to recognize and yet ignore the problem.' In an email to NBC News, Jeff Neal, a Harvard representative, explained that a committee, made up of faculty, staff and students had been established to tackle cheating, which 'is a national problem in American education'. He added: 'While the vast majority of Harvard and other students do their work honestly, beginning this year Harvard College has implemented a new, more robust strategy of communicating with all students, particularly first-year students, about the importance—and the ways to achieve—academic integrity.' In a rebuff to critics who say university has become little more than an expensive party, 84 percent of the responding undergraduates fully expected to prioritize their academics over extracurricular activities, sport, employment and their social lives. Not a single student put academics at the bottom of their list. Not content with confining themselves to their degree subject, 59 percent of incoming students expressed a desire to pursue a secondary field of study, and 36 percent hoped to learn a language.

单选题W: Since it’s raining so hard, let’s go and see the new exhibitions.M: That’s a good idea. Mary Johnson is one of my favorite painters.Q: Where does the conversation most probably take place?

单选题Everything A could destroy if he B hadn't called the C firemen when the fire D broke out .

单选题She has a small machine for ______ coffee beans.

单选题 Last summer, the missing white-letter hairstreak butterfly was spotted in Scotland for the first time in 133 years. Conservationists wondered if the creature had established a breeding colony in the country—and a new discovery suggests there is good reason to be optimistic. As Russell Jackson reports for the Scotsman, volunteer naturalists recently found a cluster of tiny white-letter hairstreak eggs on an elm tree in Lennel, a small village near the country of Berwickshire. Volunteers with the UK's Butterfly Conservation have been carefully tracking white-letter hairstreak migrations for more than ten years. The butterfly, which boasts a distinctive 'W' pattern on the underside of its wings, is native to the U.K. and was once widespread in England and Wales. But white-letter hairstreak numbers have declined drastically in recent decades, largely due to an outbreak of Dutch elm disease, an illness that took hold in the 1960s. The disease has killed millions of British elm trees, which is the food source for white-letter hairstreak caterpillars (蝴蝶或蛾的幼虫). Recently, there have been signs that the butterfly's populations are recovering. The Butterfly Conservation team has observed the white-letter hairstreak gradually spreading northwards, possibly due to warming climates. But the white-letter hairstreak is still a very rare sight in Scotland, and the volunteers who found the cluster of eggs—Ken Haydock and Jill Mills—were thrilled by the discovery. 'It was a lovely sunny morning and we were searching the elm trees by the River Tweed at Lennel when Jill called me over,' Haydock says in a Butterfly Conservation statement. 'I could see by the look on her face that she had found something. We were both smiling with disbelief and delight when we realized what Jill had found and within seconds I was fumbling in my pack for the camera—my hands were shaking!' That Haydock and Mills managed to spot the eggs is quite remarkable; according to Vittoria Traverso of Atlas Obscura, white-letter hairstreak eggs are smaller than a grain of salt. The volunteers were also excited to discover an old, hatched eggshell amid the cluster of new eggs. According to the Butterfly Conservation, this suggests that the white letter hairstreak could have been breeding in the area since at least 2016. Paul Kirkland, the director of the Butterfly Conservation's Scotland chapter, says in the statement that conservationists will 'need to have a few more years of confirmed sightings' before they can classify the white-letter hairstreak as a resident species of Scotland. 'If this happens, it would take the total number of butterflies found in Scotland to 34,' he says, 'which really would be something to celebrate.'