finger machine (手套的) 手指编结机 plain ends (未套丝的) 管材的平滑端 serrated end (管的) 收缩端 knee bend (弯管) 直角弯头 compressive curvature(喷管的) 压缩曲率 steel bulkhead (钢管的) 钢闷头 narrow neck (显像管) 细管颈 identifier circuit