填空题

In the late 1960s, many people in North America turned their attention to environmental problems, and new steel-and-glass skyscrapers were widely (36) . Ecologists pointed out that a (37) of tall buildings in a city often overburdens public transportation and parking lot (38) . Skyscrapers are also (39) . consumers, and waster, of electric power. In one recent year, the addition of 17 million square feet of skyscraper office space in New York raised the daily demand for electricity by 120,000 kilowatts—enough to (40) . the entire city of Alnaby for a day. Glass-walled skyscrapers can be especially wasteful. The heat loss (or gain) through a wall of half-inch (41) . glass is more than ten times that through a typical stone wall filled with insulation board. To (42) . the pressure on heating and air-conditioning equipment, builders of skyscrapers have begun to use double-covered (43) . of glass with silver or gold mirror films that reduce strong sunshine as well as heat gain. (44) . Skyscrapers put a severe burden on a city’s sanitation facilities, too. (45) .In Boston in the late 1960s, some people even feared that shadows from skyscrapers would kill the grass on Boston Common. Still, people continue to build skyscrapers for all the reasons that they have always built them (46) .