pentagonn.五边形Pentagon:五角大楼（美国国防部）.pentagonal icositetrahedral class五角三八面体晶族,五角三八面体类Pentagon Telecommunication Office五角大楼电信处Pentagon Counterintelligence Force五角大楼反情报部队pentagonal indexable carbide insert五角形可转位硬质合金刀片Pentagon Automated Communications System五角大楼自动通信系统Pentagon Consolidated Telecommunications Center五角大楼加固电讯中心