aboard: 在船(或飞机，车)上。如：I never went aboard a ship. broad: 为形容词，宽广的。如：He has very broad shoulders. abroad: 副词，在国外或海外。如：He often goes abroad. board: 为动词，上(船，飞机，车)。如：The passengers are boarding the plane now.
structure: 结构 system: 系统 heritage: 遗产