单选题{{B}}Text 1{{/B}} Famed singer Stevie Wonder can't see his fans dancing at his concerts. He can't see the hands of his audience as they applaud wildly at the end of his Superstition. Blind from birth, Wonder has waited his whole life for a chance to see. Recently, Wonder visited Mark Hamayan, a vision specialist. He thought that a new device currently being studied by Humayan might offer him that chance. The device, a retinal prosthesis, is a tiny computer chip implanted inside a patient's eye. The chip sends images to the brain and allows some sightless people to see shapes and colors. Wonder hoped the retinal prosthesis might work for him. "I've always said that if ever there's possibility of my seeing," said Wonder, "then I would take the challenge." Unfortunately for Wonder, that challenge will have to wait. Humayan explained that the device isn't ready for people who have been blind since birth. Their brains may not be able to handle signals from a retinal prosthesis because their brains have never handled signals from a healthy eye. The retinal prosthesis and other devices, however, show great promise in helping many other sightless people who once had vision see again. Perhaps one day soon, some formerly sightless people may be in Wonder's audience looking up—and seeing him—for the very first time. Wonder's willingness to take part in retinal prosthesis studies and the results of those studies are giving new hope to people who thought they would be blind for the rest of their lives. More than one million people in the United States are considered legally blind, meaning that their eyesight is severely impaired. Another one million are totally blind. Two types of specialized cells in the retina—rods and cones—are critical for proper vision. Light enters the eye and falls on the rods and cones in the retina. Those cells convert the light to electrical signals which travel through the optic nerve to the brain. The brain interprets those signals as visual images. Rods detect light at low levels of illumination. For instance, rods allow you to see faint shadows in dim moonlight. Cones, on the other hand, are most sensitive to color. Some diseases can damage cells in the retina. For instance, macular degeneration causes blindness and other vision problems in 700,000 people in the United States each year. The condition is caused by a lack of adequate blood supply to the central part of the retina. Without blood, the rods, cones, and other cells in the retina die. Devices such as the retinal prostheses won't prevent or cure our eye diseases, but they may help patients who have eye disorders regain some of their vision. Different forms of retinal prostheses are currently being developed. On one type, a tiny computer chip is embedded in the eye. The chip has a grid of about 2,500 light-sensing elements called pixels. Light entering the eye strikes the pixels, which convert the light into electrical signals. The pixels then send the electrical signals to nerve cells behind the retina. Those cells send signals via the optic nerve to the brain for interpretation. Many people who have had a retinal prosthesis implanted say they can see shapes, colors, and movements that they couldn't see before. "It was great," said Harold Churchey, who received his retinal prosthesis 15 years after he became totally blind. "To see light after so long—it was just wonderful. It was just like switching a light on." (572 words. Current Science. April 7, 2000)

单选题The "formal learning" refers to all learning which takes place in the classroom, regardless of whether such learning is ______ by conservative or progressive ideologies. A. secured B. attained C. manifest D. informed

单选题As one works with color in a practical or experimental way, one is impressed by two apparently unrelated facts. Color as seen is a mobile changeable thing depending to a large extent on the relationship of the color to other colors seen simultaneously. It is not fixed in its relation to the direct stimulus which creates it. On the other hand, the properties of surfaces that give rise to color do not seem to change greatly under a wide variety of illumination colors, usually (but not always) looking much the same in artificial light as in daylight. Both of these effects seem to be due in large part to the mechanism of color adaptation mentioned earlier. When the eye is fixed on a colored area, there is an immediate readjustment of the sensitivity of the eye to color in and around the area viewed. This readjustment does not immediately affect the color seen but usually does affect the next area to which the gaze is shifted. The longer the time of viewing, the higher the intensity, and the larger the area, the greater the effect will be in terms of its persistence in the succeeding viewing situation. As indicated by the work of Wright and Schouten, it appears that, at least for a first approximation, full adaptation takes place over a very brief time if the adapting source is moderately bright and the eye has been in relative darkness just previously. As the stimulus is allowed to act, however, the effect becomes more persistent in the sense that it takes the eye longer to regain its sensitivity to lower intensities. The net result is that, if the eye is so exposed and then the gaze is transferred to an area of lower intensity, the loss of sensitivity produced by the first area will still be present and appear as an "afterimage" superimposed on the second. The effect not only is present over the actual area causing the "local adaptation" but also spreads with decreasing strength to adjoining areas of the eye to produce "lateral adaptation." Also, because of the persistence of the effect if the eye is shifted around from one object to another, all of which are at similar brightness or have similar colors, the adaptation will tend to become uniform over the whole eye.

单选题Whenever we come to stay with them, we just Ulive like fighting cocks/U.

单选题 The Queen's presence imparted an air of elegance to the drinks reception at Buckingham Palace to London.

单选题Since his retirement, Peter Smith, who was ______ a teacher, has written four novels.(2013年厦门大学考博试题)

单选题If you______ the principle of democratic government to your family you will run into some obvious difficulties.(2011年南京大学考博试题)

单选题 The business of advertising is to invent methods of addressing massive audiences in a language designed to be easily accessible and immediately persuasive. No advertising agency wants to{{U}} (51) {{/U}}out an ad that is not clear and convincing to millions of people. But the agency,{{U}} (52) {{/U}}they would agree that ads should be written to sell products, disagree when it{{U}} (53) {{/U}}down to the most effective methods of doing so.{{U}} (54) {{/U}}the years, advertising firms have developed among themselves a variety of distinctive styles{{U}} (55) {{/U}}on their understanding of the different kinds of audiences they want to reach. No two agencies would handle the{{U}} (56) {{/U}}product identically. To people{{U}} (57) {{/U}}whom advertising is an exacting discipline and a highly competitive profession, an ad is{{U}} (58) {{/U}}more than a sophisticated sales pitch, an attractive verbal{{U}} (59) {{/U}}device to serve manufactures. In fact, for those who examine ads critically or professionally, products may very well be{{U}} (60) {{/U}}more than merely points of departure. Ads often{{U}} (61) {{/U}}their products, and in the{{U}} (62) {{/U}}of early advertisements for products that are no longer available, we cannot help{{U}} (63) {{/U}}consider the advertisement independently of our responses, to those products. The point of examining ads apart{{U}} (64) {{/U}}their announced subjects is not that we ignore the product completely, but{{U}} (65) {{/U}}we try to see the product only{{U}} (66) {{/U}}it is talked about and portrayed in the full{{U}} (67) {{/U}}of the ad. Certainly, it is not necessary to{{U}} (68) {{/U}}tried a particular product to be{{U}} (69) {{/U}}to appreciate the technique section and design used in{{U}} (70) {{/U}}advertisement.

单选题Noting the murder victim' s pear like figure, she deduced that the unfortunate fellow had earned his living in some ______ occupation.

单选题The appeal to file senses known as ______ is especially common in poetry.

单选题The climax in the development of a sense of trust occurs ______.

单选题It is hard to tell whether we are going to have a ______ in the economy or a recession.

单选题Cough syrups and cold remedies that are manufactured with alcohol will last much longer than those prepared with water.

单选题The vegetative forms of most bacteria axe killed by drying in air, although the different species exhibit pronounced differences in their resistance. The tubercle bacillus is one of the more resistant, and vibrio cholcra is one of the more sensitive to drying In general, the encapsulated organisms are more resistant than the non-encapsulated forms. Spores are quite resistant to drying; the spores of the anthrax bacillus, for example, will germinate alter remaining in a dry condition for years or more. The resistance of the pathogenic forms causing disease of the upper respiratory tract is of particular interest in connection with airborne infection, for the length of time that a droplet remains infective is a result, primarily, of the resistance of the particular microorganism to drying.

单选题Two thirds of the U.S. basketball players are black, and the number would be greater ______ the continuing practice of picking white bench warmers for the sake of balance.

单选题Large, multinational corporations may be the companies whose ups and downs seize headlines. But to a far greater extent than most Americans realize, the economy's vitality depends on the fortunes of tiny shops and restaurants, neighborhood services and factories. Small businesses, defined as those with fewer than 100 workers, now employ nearly 60 percent of the work force and are expected to generate half of all new jobs between now and the year 2000. Some 1.2 million small firms have opened their doors over the past six years of economic growth, and 1989 will see an additional 200000 entrepreneurs striking off on their own. Too many of these pioneers, however, will blaze ahead unprepared. Idealists will overestimate the clamor for their products or fail to factor in the competition. Nearly everyone will underestimate, often fatally, the capital that success requires. Midcareer executives, forced by a takeover or a restructuring to quit the corporation and find another way to support themselves, may savor the idea of being their own boss but may forget that entrepreneurs must also, at least for a while, be bookkeeper and receptionist, too. According to Small Business Administration data, 24 of every 100 businesses starting out today are likely to have disappeared in two years, and 27 more will have shut their doors four years from now. By 1995, more than 60 of those 100 start-ups will have folded. A new study of 3000 small businesses, sponsored by American Express and the National Federation of Independent Business, suggests slightly better odds: Three years after start-up, 77 percent of the companies surveyed were still alive. Most credited their success in large part to having picked a business they already were comfortable in. Eighty percent had worked with the same product or service in their last jobs. Thinking through an enterprise before the launch is obviously critical. But many entrepreneurs forget that a firm's health in its infancy may be little indication of how well it will age. You must tenderly monitor its pulse. In their zeal to expand, small-business owners often ignore early warning signs of a stagnant market or of decaying profitability. They hopefully pour more and more money into the enterprise, preferring not to acknowledge eroding profit margins that mean the market for their ingenious service or product has evaporated, or that they must cut the payroll or vacate their lavish offices. Only when the financial well runs dry do they see the seriousness of the illness, and by then the patient is usually too far gone to save. Frequent checks of your firm's vital signs will also guide you to a sensible rate of growth. To snatch opportunity, you must spot the signals that it is time to conquer new markets, add products or perhaps franchise your hot idea.

单选题Those persons whose religious ______heavily relied on rituals, such as infant baptism, were more likely to support the Democrats. (2015年北京航空航天大学考博试题)