科学研究简称研究，是寻求问题解释、解决的过程，这个问题可能是自然现象，也可能是社会现象或是精神现象。()

未分类题Peek through the inspection windows of the nearly 100 three-dimensional (3D) printers quietly making things at RedEye, a company based in Minnesota, and you can catch a glimpse of how factories will work in the future. It is not simply that the machines run day and night【C1】______by just a handful of technicians.【C2】______it is what they are making that shows how this revolutionary production process is【C3】______the manufacturing mainstream. 3D printers make things by building them up, a layer at a time,【C4】______a particular material, rather than【C5】______it by cutting, drilling or machining—which is why the process is also called additive manufacturing. There are many ways in which this can be done, and with only a【C6】______adjustment of software each item can be different,【C7】______the need for costly retooling of machines. This has made 3D printing a【C8】______way to make one-off items, especially prototype parts, mock-ups, small mechanical【C9】______and craft items. And that is about all that 3D printers are good for,【C10】______the doubters. Chief among them is Terry Gou, the boss of Foxconn. He thinks 3D printing is just 'a trick' without any【C11】______value in the manufacture of real finished goods, and he has vowed to start spelling his name backwards if【C12】______wrong. Mr. Gou is right about one thing: additive manufacturing is not about to replace mass manufacturing.【C13】______the technology is improving, the finish and durability of some printed items can still【C14】______what producers require. And nor can 3D printers produce millions of【C15】______parts at low cost, as mass-production lines can.【C16】______3D printers have their【C17】______which is why they are starting to be used by some of the worlds biggest manufacturers, such as Airbus, Boeing, GE, Ford and Siemens. The market for 3D printers and【C18】______is small, but growing fast. Last year it was worth $2.2 billion worldwide, up 29% from 2011. As producers become more【C19】______with the technology, they are moving from prototypes to final【C20】______.【C1】A．designedB．attendedC．introducedD．bought

未分类题【C15】A．in generalB．in briefC．in turnD．in consequence

未分类题【C4】A．dress upB．show upC．pipe upD．shut up

判断题电脑写作改变几千年来传统的写作方式。()

单项选择题人员素质测评的实施过程中，需要我们特别注意的四个问题是采用并遵守标准化的指导语、______、创造适宜的测评环境、测评双方的心理调控。

未分类题【C7】A．live throughB．give awayC．hold backD．ward off

未分类题The news about vitamins keeps getting worse. Many studies published in the last few years shows that a variety of popular supplements dont do anything to reduce the risk of developing heart disease, stroke or a variety of cancers. But what about multivitamins? These combination pills, which【C1】______10 to 30 vitamins and【C2】______, are the most popular supplements sold in America. A report published recently suggests they shouldnt be. The study【C3】______161,808 participants in the Womens Health Initiative, a long-term effort to【C4】______risk factors for cancer, heart disease and bone health in elderly women.【C5】______in the nationwide study included white, black, Asian and Native American women. They were followed for an average of nearly eight years.【C6】______, 41.5% of study participants took some version of a multivitamin. Those women were more likely to be white and college-educated, live in the West, exercise and have a lower body mass index. However, women who took multivitamins werent any more likely to【C7】______a diagnosis of breast, lung, stomach, and other cancers than were women who didnt take multivitamins. Nor were multivitamins in general helpful in【C8】______heart attacks, strokes or reducing the risk of death from any【C9】______during the study period. The research team did find one【C10】______benefit: The 3,741 women who took stress multivitamins—formulations【C11】______higher doses of several B vitamins along with an extra amount of vitamin C—were 25% less likely to have a heart attack. No other correlations between vitamins and health outcomes were statistically【C12】______. The study provides【C13】______evidence that multivitamin use has little or no【C14】______on the risk of common cancers, heart disease or total mortality in elderly women.【C15】______, researchers wondered, 'Why do millions of Americans use a daily multivitamin for【C16】______disease prevention when the supporting scientific data are weak?' Some physicians continue to【C17】______them for patients whose diets may have nutritional【C18】______. And since they dont require a prescription, many people simply【C19】______they are safe. But those assumptions may not be【C20】______, especially if people wind up overdosing on vitamins and minerals, the researchers wrote.【C1】A．generateB．representC．containD．scrape

判断题通过总结教育教学经验，既能注意教育实践中感性认识的积累和总结，又能注意教育理论指导下教育实践材料的分析研究与理性升华，提高教师的教育科学研究水平。()

未分类题Mammals vary enormously in size, from weighing less than a penny to measuring more than three school buses in length. Some groups of mammals have become very large, such as elephants and whales,【C1】______others have always been small, like primates. A new theory developed by an international team, led by Jordan Okie,【C2】______an explanation for why and how【C3】______groups of organisms are able to evolve【C4】______sizes, whereas others are not. The research team【C5】______information on how quickly an individual animal grows and used it to【C6】______how large it may get【C7】______evolutionary time. Their research was published recently. The new theory developed from the observation that some animals【C8】______fast and die young, while others take their time and mature much later. 'Fast' animals-such as mice—breed very quickly, while humans mature slowly and are relatively older when they first have children. The theory【C9】______that those species that are relatively faster are more likely to evolve a large size quicker than slow species, and that their maximum size will be greater. The research team tested their theory using the【C10】______records of mammals over the last 70 million years, examining the maximum size of each mammal group【C11】______that time, including whales, elephants, seals and primates. They found that their theory was very well【C12】______. 'Primates have evolved very slowly, and never got bigger than 1,000 pounds,' said Okie, 'The【C13】______was true of whales, which evolved their large size at the fastest【C14】______recorded.' The theory also makes predictions about the relative risks of extinction for large animals【C15】______small. The maximum size of an animal is limited by the rate of mortality in the【C16】______. Because larger animals【C17】______breed less frequently than smaller animals,【C18】______the mortality rate doubles, the maximum size is predicted to be 16 times smaller. 'This is a really surprising【C19】______,' said Okie. 'It points to another reason why many of the large animals went【C20】______after the last Ice Age, and their high risk of extinction in modern environments.'【C1】A．becauseB．whileC．ifD．and

未分类题【C18】A．in thatB．despiteC．thereforeD．if

判断题重测信度也叫稳定性系数，是估计测验跨时间的一致性的指标。用同一种测验对同一组被试先后施测两次，被试两次测验分数间的相关系数即为重测信度。()

单项选择题有一台六极三相绕线式异步电动机，在f=50Hz的电源上带额定负载运行，其转差率为0.02，电动机的同步转速为( )。 A.900r min B.1200r min C.1000r min D.1400r min

未分类题The average British people get six-and-a-half hours sleep a night, according to the Sleep Council. It has been known for some time that the amount of sleep people get has,【C1】______declined over the years. But【C2】______the average amount of sleep we are getting has fallen, rates of obesity and diabetes have soared. Could the two be connected? We wanted to see what the【C3】______would be of increasing average sleep by just one hour. So we asked seven volunteers, who【C4】______sleep anywhere between six and nine hours, to be【C5】______at the University of Surreys Sleep Research Centre. The volunteers were randomly【C6】______to two groups. One group was asked to sleep for six-and-a-half hours a night, the other got seven-and-a-half hours. After a week the researchers took blood tests and the volunteers were asked to switch sleep【C7】______. The group that had been sleeping six-and-a-half hours got an【C8】______hour, the other group slept an hour less. Computer tests designed to measure brain wave activity【C9】______that most of them struggled with mental agility tasks when they had less sleep, but the most interesting results came from the blood tests that were【C10】______. Dr Simon Archer and his team at Surrey University were【C11】______interested in looking at the genes that were switched on or off in our volunteers【C12】______changes in the amount that we had made them sleep. 'We found that【C13】______there were around 500 genes that were affected,' Archer【C14】______. 'Some which were going up, and some which were going down.' What they discovered is that when the volunteers【C15】______back from seven-and-a-half to six-and-a-half hours sleep a night, genes that are【C16】______with processes like immune response and response to stress became more【C17】______The team also saw increase in the activity of genes related to diabetes and risk of cancer. The【C18】______happened when the volunteers added an hour of sleep. So the clear【C19】______from this experiment was that if you are getting less than seven hours sleep a night and can alter your sleep habits, even one hour more, it could make you【C20】______.【C1】A．by chanceB．on averageC．at lengthD．for good

未分类题【C3】A．hang .B．crashC．landD．move

未分类题When Neil Armstrong and Buzz Aldrin returned from the moon, their cargo included nearly fifty pounds of rock and soil, which were packed in an aluminum box with seals designed to maintain the lunar surfaces low-pressure environment. But back at Johnson Space Center, in Houston, scientists discovered that the seals had been【C1】______—by moon dust. Lunar dust is fine, like a powder,【C2】______it cuts like glass. Its formed when shooting stars【C3】______on the moons surface, heating its rocks and dirt and reducing them to fine particles. Since theres no wind or water to smooth【C4】______edges, the tiny grains are sharp and uneven, and【C5】______nearly everything. 'The intruding【C6】______of lunar dust represents a more challenging engineering design issue, as well as a【C7】______issue for settlers, than does radiation,' wrote Harrison Schmitt, an Apollo 17 astronaut, in his 2006 book, 'Return to the Moon.' The dust damaged space-suits and ate away layers of moon boots. Over the【C8】______of six Apollo missions, not one rock box【C9】______its vacuum seal. Dust followed the astronauts back into their ships, too. According to Schmitt, it smelled like gunpowder and made breathing【C10】______. No one knows precisely what the extremely small particles do to human lungs. The dust not only【C11】______the moons surface, but floats up to sixty miles【C12】______it—as an outer part of its atmosphere, where particles【C13】______the moon by gravity, but are so thin that they【C14】______collide. In the nineteen-sixties, Surveyor probes filmed a glowing cloud floating just above the lunar surface during sunrise. Later, Apollo 17 astronaut Gene Cernan, while orbiting the moon, recorded a【C15】______phenomenon at the sharp line where lunar day meets night. Cernan【C16】______a series of pictures illustrating the changing【C17】______; streams of particles popped【C18】______the ground and hovered, and the resulting cloud came into sharper focus as the astronauts orbiter approached daylight. Since theres no wind to form. and【C19】______the clouds, their origin is something of a mystery. Its【C20】______that theyre made of dust, but no one fully understands how or why they do their thing.【C1】A．destroyedB．stainedC．changedD．consolidated