外科学

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

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

• 禾(rice plant)RADICAL
• 斗(threshing floor; rice threshing area)ASSOCIATIVE

To classify rice grain by measuring each type with a measuring vessel.

• ⺍(two hands (indicating learning))ASSOCIATIVE
• 冖(roof; house)ASSOCIATIVE
• 子(child)RADICAL

A child sitting under a roof with two hands diligently studying represents learning.