【单选题】In a suspension bridge, the shape of the suspension cables is parabolic. The bridge shown in the figure has towers that are 400 m apart, and the lowest point of the suspension cables is 100 m below th...
【单选题】听力原文: Over the past decade, the environmental movement has exploded onto the minds of mainstream consumers, a fact not lost on marketers and advertisers. Green advertising started in the mid-1980s whe...