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.
content: 内容;
contrast: 对比,差异;
context: 上下文
contest: 比赛,竞赛;