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powering a city its a breeze now, windmills are breaking into a new frontier. though still in its teething stages, the urban turbine is a high-tech windmill designed to generate energy from the rooftops of busy cities. lighter, quieter, and often more efficient than rural counterparts, they take advantage of the extreme turbulence and rapid shifts in direction that characterize urban wind patterns. but so far, they are being designed more for public or commercial buildings than for private homes. the smallest of the current models weigh roughly 200 kilograms and can be installed on a roof in a few hours without using a crane. problems remain, however, for example, public safety concerns, and so strict standards should be applied to any potential manufacturer. vibrations are the main problem in skyscraper-high turbine. people dont know what it would be like to work there, in an office next to one of the big turbines. it might be too hectic. 31. what are the symbols of the netherlands according to the first paragraph? b. wooden shoes and wooden windmills. d. both a and b. a. it is a windmill put on rooftops of buildings for energy generation. c. it is light and quiet and therefore more efficient. 33. the smallest models of an urban turbine b. weighs 2,000 kilograms. | 
