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To get from Kathmandu to the tiny village in Nepal, Dave Irvine-Halliday spent more than two days. When he arrived, he found villagers working and reading around battery-powered lamps equipped with light-emitting diodes, or LEDs--the same lamps he had left there in 2000. Irvine-Halliday, an American photonics engineer, was not surprised. He chose to use LED bulbs because they are rugged, portable, long-lived, and, extremely efficient. Each of his lamps produces a useful amount of illumination from just one watt of power. Villagers use them about four hours each night, then top off the battery by pedaling a generator for half an hour. The cool, steady beam is a huge improvement over lamps still common in developing countries. In fact, LEDs have big advantages over familiar incandescent (白炽的) lights as well--so much so that Irvine-Halliday expects LEDs will eventually take over from Thomas Edison’s old lightbulb as the world’s main source of artificial illumination. The dawn of LEDs began about 40 years ago, but early LEDs produced red or green glows suitable mainly for displays in digital clocks and calculators. A decade ago, engineers invented a semiconductor crystal made of an aluminum compound that produced a much brighter red light. Around the same time, a Japanese engineer developed the first practical blue LED. This small advance had a huge impact because blue, green, and red LEDs can be combined to create most of the colors of the rainbow, just as that in a color television picture. These days, high-intensity color LEDs are showing up everywhere such as the traffic lights. The reasons for the rapid switchover are simple. Incandescent bulbs have to be replaced annually, but LED traffic lights should last five to yen years. LEDs also use 80 to 90 percent less electricity than the conventional signals they replace. Collectively, the new traffic lights save at least 400 million kilowatt-hours a year in the United States. Much bigger savings await if LEDs can supplant Mr. Edison’s bulb at the office and in the living room. Creating a white-light LED that is energy-saving, cheap and appealing has proved a tough engineering challenge. But all the major lightbulb makers--including General Electric, Philips, and Osram-Sylvania--are teaming up with semiconductor manufacturers to make it happen. The author implies that villagers liked LED bulbs very much, because they ______.
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主接线采用一个半断路器接线时，电流互感器和电压互感器的配置。 关于电压互感器的配置，下列说法正确的是( )。
Crossing Wesleyan university’s campus usually requires walking over colorful messages chalked on the ground. They can be as innocent as meeting announcements, but in a growing number of cases the language is meant to shock. It’s not uncommon, for instance, to see lewd (淫荡的) references to professors’ sexual preferences scrawled across a path or the mention of the word Nig’ that African-American students say make them feel uncomfortable. In response, officials and students at schools are now debating ways to lead their communities away from forms of expression that offend or harass (侵扰). In the process, they’re butting up against the difficulties of regulating speech at institutions that pride themselves on fostering open debate. Mr. Bennet of Wesleyan says he had gotten used to seeing occasional chalkings filled with four-letter words. Campus tradition made any horizontal surface not attached to a building a potential billboard. But when chalkings began taking on a more threatening and lewd tone, Bennet decided to act. "This is not acceptable in a workplace and not acceptable in an institution of higher learning," Bennet says. For now, Bonnet is seeking input about what kind of message-posting policy the school should adopt. The student assembly recently passed a resolution saying the "right to speech comes with implicit responsibilities to respect community standards." Other public universities have confronted problems this year while considering various ways of regulating where students can express themselves. At Harvard Law School, the recent controversy was more linked to the academic setting. Minority students there are seeking to curb what they consider harassing speech in the wake of a series of incidents last spring. At a meeting held by the "Committee on Healthy Diversity" last week, the school’s Black Law Students Association endorsed a policy targeting discriminatory harassment. It would trigger a review by school officials if there were charges of "severe or pervasive conduct" by students or faculty. The policy would cover harassment based on, but not limited to, factors such as race, religion, creed, sexual orientation, national origin, and ethnicity (种族划分). Boston attorney Harvey Silverglate, says other schools have adopted similar harassment policies that are actually speech codes, punishing students for raising certain ideas. "Restricting students from saying anything that would be perceived as very unpleasant by another student continues uninterrupted," says Silverglate, who attended the Harvard Law town meeting last week. What is the typical scene found in the campus of Wesleyan University
DDU和DDP属于可适用于多种运输方式的贸易术语。 ( )
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 Schooler-- 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.\ Kimberly Rugh Talked about her son’s birthday party ______.
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