She threw a party because her husband got promoted at work.

promoted 是动词 promote 的过去分词形式。promote 由前缀 pro-（表示"向前"）和词根 mote（来自拉丁语 movere，意为"移动"）组成，字面意思是"向前移动"，引申为"提升、晋升"的意思。在这里 promoted 表示"被提升职位"的状态。