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 wil A. is a mountain climber B. went to that village to repair the lamps C. found the villagers were using the lamps he had given them D. has visited the small village several times [填空题]They felt sorry that the rain kept them from(get)______in the wheat as planned.
[单项选择]
In early 2004 eight tiny sensors were dropped from a plane near a military base in California. After hitting the ground, the sensors—also known as smart dust sensors—organized themselves into a network and quickly detected a fleet of military vehicles on the ground. They determined the direction, speed and size of a series of military vehicles traveling along the road and later transmitted the data to a computer at a nearby base camp. 我来回答: 提交
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