As soon as he got home, he unpacked his suitcase and hung up all his clothes.

unpacked 是动词 unpack 的过去式。unpack 由前缀 un-（表示"相反动作"）和动词 pack（打包）组成，字面意思是"拆开打包的东西"，即"打开行李、取出物品"的动作。