题目内容
根据《跟单信用证统一惯例》，对于信用证中的“约”量条款，数量变动幅度不超过10%。 ( )
查看答案
搜索结果不匹配？点我反馈
更多问题
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. What does Irvine-Haltiday think of LEDs
计算机系统接地线截面的选择(采用绝缘铜绞线或电缆为接地线)。 机柜与钢筋接地连接线为( )。
需要汽蒸进行初步熟处理的原料多为质软、易烂的原料。
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.\ The challenge of the school is ______.
微信支付 
支付宝支付