2021考研英语阅览限时操练题(2)

led by superconducting ceramics that may revolutionize electronics. but superconductors are just part of the picture： from house and cars to cook pots and artificial teeth， the world will someday be made of different stuff. exotic plastics， glass and ceramics will shape the future just as surely as have genetic engineering and computer science.<br><br>the key to the new materials is researchers‘ increasing

ability to manipulate substances at the molecular level. ceramics， for example， have long been limited by their brittleness. but by minimizing the microscopic imperfections that cause it， scientists are making far stronger ceramics that still retain such qualities as hardness and heat resistance. ford motor co. now uses ceramic tools to cut steel. a firm called kyocera has created a line of ceramic scissors and knives that stay sharp for years and never rust or corrode.<br><br>a similar transformation has overtaken plastics. high-strength polymers now form bridges， ice-skating rinks and helicopter rotors. and one new plastic that generates electricity when vibrated or pushed is used in electric guitars， touch sensors for robot hands and karate jackets that automatically record each punch and chop. even plastic litter， which once threatened to permanently blot the landscape， has proved amenable to molecular tinkering. several manufacturers now make biodegradable forms some plastic six-pack rings for example， gradually decompose when exposed to sunlight. researchers are developing ways to make plastics as recyclable as metal or glass. besides， composites &ndash plastic reinforced with fibers of graphite or other compounds &ndash made the round-the-world flight of the voyager possible and have even been proved in combat： a helmet saved an infantryman‘s life by deflecting two bullets in the grenada invasion.<br><br>some advanced materials are old standard with a new twist. the newest fiberoptic cable that carry telephone calls cross-country are made of glass so transparent that a piece of 100 miles thick is clearer than a standard pane.<br><br>but new materials have no impact until they are made into products. and that transition could prove difficult， for switching requires lengthy research and investment. it can be said a firmer handle on how to move to commercialization will determine the success or failure of a country in the near future.<br>