外层空间

• 夕(evening; crescent moon (pictographic))RADICAL
• 卜(divination; fortune-telling)PHONETIC

Evening outside divining fortunes under the moon — that's an external affair.

• 尸(corpse; roof (covering))RADICAL
• 云(cloud)PHONETIC

Layers of houses stacked on top of each other like tiered clouds beneath a roof.

• 穴(row; gap)RADICAL
• 工(craftsman; work)PHONETIC

An empty cave with nothing inside is just hollow space.

• 門(door; leaf)RADICAL
• 日(sun; light)ASSOCIATIVE

A beam of sunlight shining through a crack in the door creates the empty space in between.