单选题
The towers of a suspension bridge serve as a rigid framework to which the cables are attached.
【正确答案】
B
【答案解析】framework：框架；基本结构。skeleton：骨架；骷髅。His constructions are centered around steel skeletons．他的建筑以钢骨架为中心。boundary：分界线。territorial boundaries：领土边界。enclosure：围绕；围墙。material：材料。