共用题干 第三篇Weaving with LightIn the Sierra Madre mountain range of west central Mexico,the native Huichol people live much the way their ancestors did一without electricity,That’s because it's too expensive to string power lines to the remote mountain areas where they live.To help support themselves,the Huichol create beautiful artwork. They sell their art in cities hundreds of miles away from their villages.And without electricity一at home or on the road,they can only work during daylight hours?When it gets dark,they must stop whatever they'redoing.Now，a team of scientists,designers,and architects is using new technologies to provide the Huichol with light after the sun sets.The scientists'technique involves weaving tiny electronic crystals into fabrics that can be made into clothes,bags,or other items.By collecting the sun’s energy during the day,these lightweight fabrics provide bright white light atnight一 Their inventors have named the fabrics" Portable(轻便的)Lights."Portable Lights have the potential to transform the lives of people without electricity around the world.At the core of Portable Lights technology are devices called high-brightness light-emitting diodes(高亮 度发光二极管),or HB LEDs. These tiny lights appear in digital clocks, televisions, and streetlights.LEDs are completely different from the light bulbs(灯泡).Most of those glass bulbs belong to a type called incandescent lights(白炽灯).Inside, electricity heats a metal coil(线圈)to about 2. 200 degrees Celsius.At that temperature,bulbs give off light we can see.Ninety percent of energy produced by mnean- descent lights,however,is heat一and invisible.With all that wasted energy,bulbs burn out quickly. Theyare also easily broken.LEDs,on the other hand,are like tiny pieces of rock made up of molecules(分子)that are arranged in a crystal structure.When an electric current passes through a LED,the crystal structure produces light. Un- like incandescent bulbs,they can produce light of various colors.Within a LED,the type of molecules and their particular arrangement determine what color is produced. The Huichol don't use electricity because ________.
A.it is too difficult for them to change their lifestyle B.they know nothing about it C.it costs too much to string power lines D.they don't need it正确答案C
